Submersing a rig

[smracer]

I was wondering if it would be possible to submerge a mining rig in pure water to keep it cool.

I would think you would have to disable all fans which would save some energy as well.

Anyone have any experience with this?

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[P4man]

Great idea if you like to kill all your hardware. If you want to submerge it, at least use mineral oil, but even then the consensus is that its not a good idea. Its expensive, messy and it will not cool as good as air cooling. If you want silence above all else, and dont mind plumbing an oil pump, filter and oil radiator, it can be done though.

[PrintCoins]

I was wondering if it would be possible to submerge a mining rig in pure water to keep it cool.

I would think you would have to disable all fans which would save some energy as well.

Anyone have any experience with this?

Heat transfer between metal and air is not as fast as metal and liquid, so you are on the right track. You just need to use something other than water which is corrosive and conductive (unless distilled). Water is not good to have in your computer.

Try this:
http://duckduckgo.com/?q=oil+cooled+pc

[bitcoinnoob101]

you can do this if you use mineral oil i have seen it done but i am not sure how good it is long term for the system

[casascius]

I would expect that even if you started out with pure water, that enough substance would dissolve off the equipment and into the water to make it not stay pure for very long.  It takes very little impurity to make water conductive.  You would need an endless stream of distilled water.

[smracer]

Why does that guy that submersed his computer in mineral oil still have the fans running? 

[bitcoinnoob101]

even laboratory grade pure H2O that is used in the electronics industry witch is made using a system several times more pure that 7 step reverse osmosis would still cause problems and be prohibitively expensive to boot

[bitcoinnoob101]

when it is submerged it it still functions the same way the heat heats the oil and it needs to circulate to keep it cool the oil in this case just takes the place of the air in air cooled systems

[jake262144]

In pure oil you must mean.
Or in some non-conductive water-cooling liquid. Those are pretty expensive though.
If you actually fancy using water you're on your way to frying the rig.

The whole operation will likely by extremely messy and destroy any resale value of your equipment.
There's a reason liquid cooling isn't done this way, you know.

[smracer]

well I guess that idea won't save any money.

I have read about google moving server farms so they are close to hydroelectric dams.

I have personally spoken to people that live within a few miles of large hydroelectric dams and they pay .01/kwh for electricity.

Also I wonder if using a nat gas generator could save mining costs due to the low cost of nat gas right now.

[PrintCoins]

Why does that guy that submersed his computer in mineral oil still have the fans running?  

<this was in reference to the video at the top of the DDG results>

You need need to circulate the heat away from things. Instead of pushing air, they are pushing oil. Fans don't cool things (even in air) they move the heat that builds around your devices away. Oil will pull the heat out of your devices quicker.

A good thing to note in the video is that this is perfectly silent. This is probably a blessing to many miners that have a continual din in the background.

It doesn't look like the radiator is needed, but just helps a little more.

Keep in mind, your room that you have this in will still be exactly as hot as before. This just makes the local area around the chips drop to the ambient temperature in the room faster. (Rules of thermodynamics still apply).

Interestingly, this probably would make running a rig outside a better option. Put an inch of space below your hardware in the tank for any possible accumulated water, put a lid on it, and it should be able to weather the outside world better than a machine not suspended in an oil bath. (But please, keep it out of direct sun.)

[P4man]

It doesn't look like the radiator is needed, but just helps a little more.

A radiator will be absolutely crucial. Otherwise you will just be making a large fryolator to fry french fries in.

[jake262144]

A radiator will be absolutely crucial. Otherwise you will just be making a large fryolator to fry french fries in.

"fryolator", beautifully said P4
Robokhr, you transfer the heat from the rig to the oil tank. Now what? The heat will build up unless you transfer it away.

[PrintCoins]

A radiator will be absolutely crucial. Otherwise you will just be making a large fryolator to fry french fries in.

"fryolator", beautifully said P4
Robokhr, you transfer the heat from the rig to the oil tank. Now what? The heat will build up unless you transfer it away.

Wouldn't the surface area of the oil and tank quickly dissipate the heat? If you turn off a deep frier, its temperature drops pretty fast (if not insulated).

[P4man]

Wouldn't the surface area of the oil and tank quickly dissipate the heat? If you turn off a deep frier, its temperature drops pretty fast (if not insulated).

Yeah, but you dont keep the miner turned off, do you?

People have tested this in aquaria, and even standard gaming PCs with a single videocard will heat up the oil to 50+C.
edit look here:
http://www.youtube.com/watch?v=NXdvHA3tr5U

Cant tell what videocard that is, but its either IGP or something really lowend. After a few hours he stopped the test when the oil reached 50C.
An 800+W mining rig will probably make it literally boil.

A square box just doesnt have enough surface area and no airflow over it to get rid of that kind of heat. Hermetically seal your mining PC and see what happens. Nothing good I assure you (even though an alu case is a far better heatconductor than a plexiglass one)

[casascius]

I have an outdoor hot tub that consumes lots of electricity... if I had a feasible way to dump my mining output into the hot tub (heat I already want to pay for), I would still be mining.  (And yes I could probably rig my video cards with copper tubing i.e. DIY watercooling, but it's not a worthwhile priority for me.)

[P4man]

Thats easy. Fill your hot tub with mineral/baby oil. Seriously, think about it

[SgtSpike]

Guys... Im pretty sure he wants to put it in a water proof box. And sink into a pool of Really cold water

I'm pretty sure not, since he specifically mentions "pure" water.

[RandyFolds]

I would expect that even if you started out with pure water, that enough substance would dissolve off the equipment and into the water to make it not stay pure for very long.  It takes very little impurity to make water conductive.  You would need an endless stream of distilled water.

Deionized water is a very aggressive solvent, meaning that it will strip things right out of the air. It is pretty much instantly ionized when you put it into a container unless it is quality borosilicate.

[jake262144]

The problem with outdoor cooling is dirt and condensation, but a sealed oil submerged computer could be put outside into brutally cold weather.  Some very inhospitable places could become prime data centers.

...until you need to hot-swap a hard drive double-quick

Wouldn't the surface area of the oil and tank quickly dissipate the heat? If you turn off a deep frier, its temperature drops pretty fast (if not insulated).

Dissipate a few hundred Watts (at best) worth of heat by surface area? Surely you must be joking.


Are we supposed to have a sensible thread here or some goddarned fantasy?

[byronbb]

lol from youtube comments:

put 4 gtx 480, overclock them, and then you would be able to make french fries in it.

[elrodvoss]

I have actually looked into Oil submersion cases for several years and done some tests with them as well.

Ive never had the guts to drop 1200 computer system into a vat of oil, mostly that once you do, it takes ALOT of clean up afterwards and voids about every warranty there is.

A good site that has made custom cases for oil cooled systems is:

http://www.pugetsystems.com/submerged.php

They been doing it for a while and has gone from a modified fish tank to a fully customized case.


You can drop anything into the oil except anything that has a physical motor that spins.  So Fans, Hard Drives, CD/DVD Drives, etc.  You can drop in the motherboard, SSD, CPU, RAM, GPU, even the PSU (the fan is only to cool the heat sinks in the PSU).  Plus you wont get shocked.

So you could get a big plastic tub, put your system into the tub and start filling the tub with oil and it will keep working.  You still need something to circulate the oil or you will get hot spots and the oil will start to heat up.  Now you put your rig inside a big aluminum box with fins and that would keep it "cooler".

The site above will have some nice videos that may impress you.

-elrodvoss

[DeathAndTaxes]

Guys... Im pretty sure he wants to put it in a water proof box. And sink into a pool of Really cold water

That would do nothing.  The rig would cook inside the insulating air.  Air is a horrible heat transfer mechanism.  I mean horrible.  Insulation isn't what keeps your house warm.  Insulation just traps air which is amazingly good insulator.

[SgtSpike]

I have actually looked into Oil submersion cases for several years and done some tests with them as well.

Ive never had the guts to drop 1200 computer system into a vat of oil, mostly that once you do, it takes ALOT of clean up afterwards and voids about every warranty there is.

A good site that has made custom cases for oil cooled systems is:

http://www.pugetsystems.com/submerged.php

They been doing it for a while and has gone from a modified fish tank to a fully customized case.


You can drop anything into the oil except anything that has a physical motor that spins.  So Fans, Hard Drives, CD/DVD Drives, etc.  You can drop in the motherboard, SSD, CPU, RAM, GPU, even the PSU (the fan is only to cool the heat sinks in the PSU).  Plus you wont get shocked.

So you could get a big plastic tub, put your system into the tub and start filling the tub with oil and it will keep working.  You still need something to circulate the oil or you will get hot spots and the oil will start to heat up.  Now you put your rig inside a big aluminum box with fins and that would keep it "cooler".

The site above will have some nice videos that may impress you.

-elrodvoss

Well, I can see why a HDD or CD/DVD drive wouldn't work (HDD needs to be air inside, and there's those holes that say "DO NOT PLUG", and CD/DVD is obvious), but there's no reason you can't have a couple of fans running inside the system, including the one in the PSU.  It won't hurt the fans.  There's plenty enough oil to keep the fan motors cool, plus free lifetime lubrication!

[chromeguy]

i would rig it similar to current watercooled PC systems. using water as a heatsink, complete with pumps & radiator (or pipe it outside to your hottub)

otherwise you need to fork out huge bucks for the fully submersible oil solution like those guys did with that supercomputer.

[RandyFolds]

i would rig it similar to current watercooled PC systems. using water as a heatsink, complete with pumps & radiator (or pipe it outside to your hottub)

otherwise you need to fork out huge bucks for the fully submersible oil solution like those guys did with that supercomputer.

The big bucks aren't for the fully submersible solution, they are for the media that you do the submersing in. Standard computer parts, aside from platter hard drives and optical drives can all take the plunge without issue.

[SgtSpike]

i would rig it similar to current watercooled PC systems. using water as a heatsink, complete with pumps & radiator (or pipe it outside to your hottub)

otherwise you need to fork out huge bucks for the fully submersible oil solution like those guys did with that supercomputer.

If I understand you correctly, you mean pumping oil through a watercooling system?

If so, that's a very bad idea.  Mineral oil has much worse heat conduction than water.  You'd be making a liquid cooling system that is much more expensive than water cooling, and also much less efficient.

[chromeguy]

i would rig it similar to current watercooled PC systems. using water as a heatsink, complete with pumps & radiator (or pipe it outside to your hottub)

otherwise you need to fork out huge bucks for the fully submersible oil solution like those guys did with that supercomputer.

If I understand you correctly, you mean pumping oil through a watercooling system?

If so, that's a very bad idea.  Mineral oil has much worse heat conduction than water.  You'd be making a liquid cooling system that is much more expensive than water cooling, and also much less efficient.

lol no, just watercooling.
which, imo, is an awful lot of mucking around to achieve slightly better cooling than a big heatsink.

I have looked into active cooling (peltiers) but there are condensation issues & they also suck alot of power on their own.

better really to just underclock until peak mh/$/power efficency & just keep buying more and more of them, rather than pressing one unit harder & harder??

[SgtSpike]

i would rig it similar to current watercooled PC systems. using water as a heatsink, complete with pumps & radiator (or pipe it outside to your hottub)

otherwise you need to fork out huge bucks for the fully submersible oil solution like those guys did with that supercomputer.

If I understand you correctly, you mean pumping oil through a watercooling system?

If so, that's a very bad idea.  Mineral oil has much worse heat conduction than water.  You'd be making a liquid cooling system that is much more expensive than water cooling, and also much less efficient.

lol no, just watercooling.
which, imo, is an awful lot of mucking around to achieve slightly better cooling than a big heatsink.

I have looked into active cooling (peltiers) but there are condensation issues & they also suck alot of power on their own.

better really to just underclock until peak mh/$/power efficency & just keep buying more and more of them, rather than pressing one unit harder & harder??

Oh, watercooling, but using a pool as a reservoir then?  That would work, so long as you kept your pumps and lines nice and free from algae and such.

I never really understood the draw of watercooling myself.  If you have a lot of money to burn, I guess. 

[DeathAndTaxes]

I never really understood the draw of watercooling myself.  If you have a lot of money to burn, I guess.  

Or other things are more important than simply pure performance at any noise level.

If you want max performance at cheapest possible performance then nothing beats air.  Crank the fans up so it sounds like an industrial band saw and it can't be beat.

I have 4 rigs in the garage running like that.  In my office I also have a workstation w/ 4x 5970 in a closed case which is quieter than a desk fan.  In the winter in quietly produces 3.1GH and dumps 4000 BTU into the room.  In the summer I move the radiator outside (though window) and it dumps the 4000 BTU outside the house.

[SgtSpike]

I never really understood the draw of watercooling myself.  If you have a lot of money to burn, I guess.  

Or other things are more important than simply pure performance at any noise level.

If you want max performance at cheapest possible performance then nothing beats air.  Crank the fans up so it sounds like an industrial band saw and it can't be beat.

I have 4 rigs in the garage running like that.  In my office I also have a workstation w/ 4x 5970 in a closed case which is quieter than a desk fan.  In the winter in quietly produces 3.1GH and dumps 4000 BTU into the room.  In the summer I move the radiator outside (though window) and it dumps the 4000 BTU outside the house.

Fair enough. 

[rjk]

I never really understood the draw of watercooling myself.  If you have a lot of money to burn, I guess.  

Or other things are more important than simply pure performance at any noise level.

If you want max performance at cheapest possible performance then nothing beats air.  Crank the fans up so it sounds like an industrial band saw and it can't be beat.

I have 4 rigs in the garage running like that.  In my office I also have a workstation w/ 4x 5970 in a closed case which is quieter than a desk fan.  In the winter in quietly produces 3.1GH and dumps 4000 BTU into the room.  In the summer I move the radiator outside (though window) and it dumps the 4000 BTU outside the house.

+1, that's why servers tend to be so loud. They have specially designed airflow paths and extremely high velocity fans.
Water is useful only to keep the noise down.

[P4man]

Im actually reconsidering my position on this and looking into submerging my rigs for when summer comes.

Here is the thing, I have a large Koi pond (50K liter) next to the shed where I would want to put my miners this summer.  And it wouldnt hurt to warm the pond water during fall and winter, even if the effect will be minimal in the best case. Even with a perfect heat exchange, 2000W is going to do next to nothing to the overall water temperature in the pond, but raising the temperature in the filters is beneficial to the filtering process, every degree helps.

Ill have to expand the filtration system for the pond anyway and  I was considering putting a few large (1000L) settling tanks in the shed. By itself, I wouldnt have expected that to do much, if anything, unless perhaps if I created an air duct of sorts around the miners to concentrate the warm air, and blow that warm air through one of the (open) tanks; i already have a 160L/hour air pump, I could add another one for that purpose. It wouldnt be much of a settling tank anymore then, and I guess it wouldnt do too much to reduce ambient heat either. or?

I guess the more efficient thing to do is submerge my rigs in mineral oil, pump the oil through a radiator which is suspended in a settling tank or filter  tank (Im using 300 liter rain barrels for biofiltering, the filter has a pretty high volume, up to 25K liter per hour).

A few questions, not sure if anyone here can help me with

- how toxic is mineral oil? Or would vegetable oil be better here? I dont fancy the idea of a small leak killing all my fish. I remember reading that a cheap way to buy large quantities of oil for submerged cooling is buying them as... horse laxative. I cant imagine a horse laxative being excessively toxic... ?

- what kind of hoses does one need? Do you need a special kind of rubber or plastic for oil? From the shed to the filtering installation is a fair few meters

- any suggestions on oil filtering?

- does anyone have any idea of dimensioning this? I got no clue how big a pump (pressure and flow rate) or radiator I would need. If it helps, by then I plan on having ~2000W worth of mining gear. The pond water rarely gets over 25C and more typical is 20C  and the water in the filter would have no time to heat up significantly because of the high flow rate. I would *guess* keeping the oil below 35-40C would be good enough to keep the cards reasonably cool, although that is more guesswork on my part.

ANy thoughts or ideas on the matter would be appreciated.

[P4man]

Okay I did some research myself. Toxicity is not a problem with pure mineral oil. you can even drink the stuff.

As for capacity planning; Lets assume I only submerge my GPUs (thats what I plan, just place them inverted with extenders so only the gpu's "swim"), lets put it at 1000W worth of GPUs in a 100L tank.lets look at the heating of the oil. I found this:

http://make-biodiesel.org/Biodiesel-Chemistry/time-to-heat-oil.html

From the above link:
Time in hours = 0.5 X Number of Liters X Temperature rise in °C / by element wattage

Solving that for temperature rise:
Temperature rise per hour = 1000W / ( 0.5 * 100L) = 20C per hour or 0.333C per minute.

Thats considerably less than I would have thought.

Lets assume a hot summer day with 35C ambient air temperature and my pond water being at 25C.

assume the submerged radiator manages to cool the oil to 10C above water temp, so to 35C.
I want the oil in mining rig to remain below 50C. Thats a 15C difference
That means I have to turn over the 100L every 5 minutes. So Id need ~1200L/hour throughput.
Actually, the amount of oil used in the rig theoretically wouldnt matter here.

Anyway, some googling found me this:

http://www.ebay.com/itm/350GPH-DC12V-80C-Brushless-Magnetic-Oil-Water-Pump-/160560267427?pt=BI_Pumps&hash=item25622340a3

Pretty much spot on for the capacity I just calculated, although that probably means its not enough when you factor in pump head and the fact the stated throughput is probably for water, not oil.

Still, seems quite doable with all the above assumptions. Looks like all I need is a pump similar to that one, but probably 2x or so as powerful, some (car) oil radiator and some tubing. Most of the stuff seems fairly inexpensive. Oh and Id need a filter somehow, as there is no way to make this setup airtight if Im only going to submerge the GPUs.

Question that remains; with 50C oil temperature, what would my GPU temps be like? Although it is probably different, can anyone using watercooling shed some light on the relationship between water temperature and GPU temps?

[JA37]

How about a little love for "Bubbles"? From 1985.
http://en.wikipedia.org/wiki/Cray-2

[DeathAndTaxes]

Why not just use a traditional water cooling rig w/ a heat exchanger?
http://www.koolance.com/water-cooling/product_info.php?product_id=944

As far as what temps are GPUs.  In watercooling (and I would imagine oil cooling too) water is such a good heat conductor that everything in the loop is within 1 or 2 degrees of everything else.  So if the oil reaches equilibrium around 50C then the GPU would be 50C.

Another way to look at it in reverse.  Say you pond can dissipate more thermal energy than your rigs can produce.  The pond water is 25C.  In the heat exchanger above using 7 LPM pumps (and water) we can transfer ~1600W of thermal energy and keep delta T at <=6C.  This means the hot loop will be in equilibrium at ~ 31C.   

In air cooling the GPU core temp being higher than the exhaust air temp is merely an effect of the poor heat conductivity of air.  If you used enough air (say thousands of cfm of airflow) you could get the input, gpu core, and exhaust air to all be roughly the same.

assume the submerged radiator manages to cool the oil to 10C above water temp, so to 35C.

Assumming you have a properly sized radiator even if you were air cooling the radiator you can keep the delta T <10 C.  With a liquid to liquid transfer you could have a much lower delta T.  <5C or even 2C is possible.

If the radiator will be submerged in water you likely will get better heat transfer with a heat exchanger.  Radiators are designed assuming they will be used to force air through fins to acheive heat transfer.  

[P4man]

Why not just use a traditional water cooling rig w/ a heat exchanger?

Price mostly. And convenience. Equipping 6 or 10 cards with full covers for watercooling is expensive, and it could be hard to find covers for all my cards. Remember I run rat rigs thrown together with leftover parts and then I plug in whatever 58x0 card I can find cheaply. I have like no 2 identical cards, and thats only gonna get worse .

As far as what temps are GPUs.  In watercooling (and I would imagine oil cooling too) water is such a good heat conductor that everything in the loop is within 1 or 2 degrees of everything else.  So if the oil reaches equilibrium around 50C then the GPU would be 50C.

Some more googling suggested that too. Well, up to 5-7C delta. This is getting more and more exciting .

If the radiator will be submerged in water you likely will get better heat transfer with a heat exchanger.  Radiators are designed assuming they will be used to force air through fins to acheive heat transfer. 

Heat exchangers require I pump water through them. Thats probably not a good idea, considering its pond water; its gonna clog sooner or later, even if I were to pump "clean" water from the end of the filter (and Id rather heat the beginning of the cycle to help the aerobic process).  My filters are connected with 130 mm pipes, that doesnt clog so easily . Moreover, it requires 2 pumps, one for the oil, one for the water. Thats 2 points of failure.

 Then there is also... price. A decent sized heat exchanger is not that cheap. I may not need a big one from an efficiency point of view, but Id need one that doesnt clog. Instead I could buy one, or heck, should it prove necessary or useful,  several oil coolers from a car junk yard for next to nothing, or even if you buy them new, something like this:
http://www.ebay.com/itm/UNIVERSAL-15ROW-10AN-TRANSMISSION-RADIATOR-TURBO-ENGINE-OIL-COOLER-ALUMINUM-BLUE-/160721146846?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item256bba13de

isnt gonna break the bank, and I cant see how that would not work when submerged in relatively fast flowing and air bubbling 20-25C water. Like you said, water is a much better heat conductor than air, if it can cool the oil by blowing air over it, its gonna work a hole lot better submerged - I think.

Anyway, Ill probably setup a small scale experiment next month with a single spare card (8800GT) to see what happens. Still have to figure out where to best buy some suitable oil, hoses,  think of a filtration system and come up with a layout thats not completely unworkable. Its not gonna be pretty with all the motherboards suspended inverted above an oil bath, but if it works,  who cares

[RandyFolds]

2000w will more than likely impact 10,000 gallons, though it wholly depends a lot on surface area. I had a 4,500g outdoor reef running 2000 watts of inline heater and it would keep the tank at 76-78 even when it was ~50F ambient and was still kicking off. The reef was lit with LED so there was almost zero infrared contributing to that. Water is an incredibly good insulator.

[DeathAndTaxes]

2000w will more than likely impact 10,000 gallons, though it wholly depends a lot on surface area. I had a 4,500g outdoor reef running 2000 watts of inline heater and it would keep the tank at 76-78 even when it was ~50F ambient and was still kicking off. The reef was lit with LED so there was almost zero infrared contributing to that. Water Air is an incredibly good insulator.

The water rose in temp because it was a good conductor and the air wasn't.  Thus the thermal energy gets "trapped" in the water and the temp rises.

Water is a horrible insulator.  As an example a warm jacket isn't what keeps you warm.  A warm jacket traps air which keeps you warm.  Now take same jacket and soak it (even in hot water), put it on and walk outside.  Brrr.  The water "shotcuts" any insulation allows a highly conductive path between your internal body heat and the very cold outside air.

[RandyFolds]

2000w will more than likely impact 10,000 gallons, though it wholly depends a lot on surface area. I had a 4,500g outdoor reef running 2000 watts of inline heater and it would keep the tank at 76-78 even when it was ~50F ambient and was still kicking off. The reef was lit with LED so there was almost zero infrared contributing to that. Water Air is an incredibly good insulator.

The water rose in temp because it was a good conductor and the air wasn't.  Thus the thermal energy gets "trapped" in the water and the temp rises.

Water is a horrible insulator.

Insulator was the wrong word, but now I need you to explain something. Would the layer of water trapped by a wetsuit be considered an insulator, or is the insulating going on in the neoprene? Wetsuit without that trapped layer doesn't do anything.

Fucking thermodynamics...how does it work?

My point was that dumping a constant 2000w into a body of water will heat it, and I am not sure ambient temperatures and airflow will be enough to 'exhaust' it, so to speak. Throw the sun into the mix and you are going to have some wild daily temperature swings to the detriment of the fishes health.

[P4man]

2000w will more than likely impact 10,000 gallons, though it wholly depends a lot on surface area.

I dont believe so. the pond is not that deep. Its bowl shaped, no deeper than 1m60. Half the pond (by surface) is less than waist deep.   Surface area is 60m2. Then there is the fact I have a DIY "trickle tower"/ proteine skimmer thats designed to  expose the water to air and *lots* of aeration in general (heavy duty air pump in the filters and in the pond).  When I turn on all my pumps on a cold autumn day, I can easily decrease the water temperature by several degrees in a single day, 2000W isnt going to offset that.  Im not sure 20Kw would.

Anyway, heating the pond is not the objective. Heating the water in the filters would be quite a useful by-product, particularly in spring, although Im not expecting much difference even there. Too much flow. One can do the math, the filter barrels excluding filter material are probably around 200L and I believe are turned around every 4 minutes. At 2000W that is  ~ +0.5C. Better than nothing, but not impressive.

[DeathAndTaxes]

Insulator was the wrong word, but now I need you to explain something. Would the layer of water trapped by a wetsuit be considered an insulator, or is the insulating going on in the neoprene? Wetsuit without that trapped layer doesn't do anything.

The water in wetsuit isn't used for insulation.  A dry suit (not a dry wetsuit but an actual drysuit) will always be superior but dry suits are expensive, complicated (the air compresses at depth), and require a lot of maintenance.  It is the neoprene which provides insulating properties.  Technically it is the air bubbles in the neoprene which provide the insulation (air is on the best low cost insulators, and water is one of the best low cost conductors).  This is why as you dive deeper a wet suits becomes less effective.  The water pressure compresses the bubbles in the neoprene reducing the insulating value.  You can partially compensate with thicker neoprene or use a dry suit.

The "wet" in a wet suit keeps it simple.  The suit doesn't need to be "perfect fit" just snug enough to minimize water exchange.  The water layer aids in comfort and since water is a conductor is spreads around any heat loss.  For most diving it is simply "good enough", however if you have ever had a wet suit which is torn you will quickly find out how bad of an insulator water is.

My point was that dumping a constant 2000w into a body of water will heat it, and I am not sure ambient temperatures and airflow will be enough to 'exhaust' it, so to speak. Throw the sun into the mix and you are going to have some wild daily temperature swings to the detriment of the fishes health.

Yeah not sure how big the body of water would need to cushion the temp swings.   Since water is such a good conductor of heat what matters is how well the pond can "exhaust" the heat into the atmospshere.   I also have no idea how much of a temp swing the fish can tolerate.  

I guess one could get a ballpark figure by measuring the pond temp in summer at dawn and noon.  The rise in temp ~= thermal energy from sun.  Figure out solar insolation, and number of hours and you could turn that into wattage.  i.e. pond got x watts from the sun and the pond temp rose y.  That might give p4man at least the magnitude we are looking out.    With only a 5C rise in temp can the pond dissipate 100W, 1000W, 10,000W, etc?

[P4man]

I guess one could get a ballpark figure by measuring the pond temp in summer at dawn and noon.  The rise in temp ~= thermal energy from sun.  Figure out solar insolation, and number of hours and you could turn that into wattage.  i.e. pond got x watts from the sun and the pond temp rose y.  That might give p4man at least the magnitude we are looking out.    With only a 5C rise in temp can the pond dissipate 100W, 1000W, 10,000W, etc?

Im not worried about that in the least. Temperature difference between bottom (where I pump most of the water) and top of the  pond can be 5-10C difference just from the sun. Between morning and afternoon you can add another 5+C to that when my filters are running. Fish dont mind. They will just swim where they feel most confortable, and if anything, Koi like warmer water than what I can offer them. They thrive when the water is ~30-35C, Ill never get there, except for some weeks per year at the top of the pond...

Once best avoids sudden temperature shocks, like from a hot bassin to a cool pond without some acclimatisation time, but intra day variance is not an issue. They are river carp, its not like you will not find huge temperature differences in a fast flowing shallow river.

[DeathAndTaxes]

Im not worried about that in the least. Temperature difference between bottom (where I pump most of the water) and top of the  pond can be 5-10C difference just from the sun. Between morning and afternoon you can add another 5+C to that when my filters are running. Fish dont mind. They will just swim where they feel most conformable, and if anything, Koi like warmer water than what I can offer them. They thrive when the water is ~35C, Ill never get there.

Sounds good.  Also if you wanted an added layer of security you could rig a temperature switch to the power for the rigs.  If temp in pond got above say 40C it would kill power to rigs.

[PrintCoins]

Wouldn't an fish tank filter :



do just as well if not better than a radiator at cooling down the oil. You would of course take out the actual filters, and just have it as a way to pull oil out of the tank and pour it through the air back into the tank.

This puppy is on sale for $29 bucks and can turn over 350 GPH of water (probably less for oil)
http://www.amazon.com/Marineland-Penguin-Power-Filter-70-Gallon/dp/B0009IMDQM/ref=pd_bxgy_petsupplies_img_b

Don't forget to decorate your tank:

[RandyFolds]

Insulator was the wrong word, but now I need you to explain something. Would the layer of water trapped by a wetsuit be considered an insulator, or is the insulating going on in the neoprene? Wetsuit without that trapped layer doesn't do anything.

The water in wetsuit isn't used for insulation.  A dry suit (not a dry wetsuit but an actual drysuit) will always be superior but dry suits are expensive, complicated (the air compresses at depth), and require a lot of maintenance.  It is the neoprene which provides insulating properties.  Technically it is the air bubbles in the neoprene which provide the insulation (air is on the best low cost insulators, and water is one of the best low cost conductors).  This is why as you dive deeper a wet suits becomes less effective.  The water pressure compresses the bubbles in the neoprene reducing the insulating value.  You can partially compensate with thicker neoprene or use a dry suit.

The "wet" in a wet suit keeps it simple.  The suit doesn't need to be "perfect fit" just snug enough to minimize water exchange.  The water layer aids in comfort and since water is a conductor is spreads around any heat loss.  For most diving it is simply "good enough", however if you have ever had a wet suit which is torn you will quickly find out how bad of an insulator water is.

I've done a lot of diving with both wet and dry suits ('fuck Lake Superior' is all I can really say about that), I just wasn't hip to how the liquid fit into the insulating picture. I suppose I should have pieced it together, what with needing a new wetsuit every six months due to compression. Southern California's got some chilly water, but dry suits absolutely suck...turn your head too far and you're wearing wool soaked with icewater.

I was an AAUS diver for a bunch of years and people are always disgusted by the concept of pissing in your wetsuit...all I can say is when you have to dive at five in the morning in 10c water, it is the only relief you are going to get...even a 7mil with an insotherm and a hooded vest won't keep you warm in that shit.

[P4man]

Sounds good.  Also if you wanted an added layer of security you could rig a temperature switch to the power for the rigs.  If temp in pond got above say 40C it would kill power to rigs.

Above 40C? Heh. Maybe I need a picture here to help you visualize 50K liter. Here is half the pond half drained for maintenance this spring:






A few gpus arent going to cause that to overheat .

Im much more worried about leaking. Ill probably add a floater switch that shuts everything down if the oil level drops. And probably an electric valve as well.

[RandyFolds]

That is a baller pond. Start the aquaculture op!

[P4man]

Wouldn't an fish tank filter :
do just as well if not better than a radiator at cooling down the oil.

Definately not.  Its just a waterfall, all that matter is the surface area you produce, and that isnt much. Moreover, insummer inside the shed it already gets to 35+C without help from mining rigs, and I were to dump all the heat in there, it would get a lot hotter. And then you only have (hot) air to cool the oil, thats not nearly as efficient as cool water.

[P4man]

That is a baller pond. Start the aquaculture op!

Not sure what you mean. If you think there is not enough plants in the water, keep in mind thats early spring before most of the plants and lillies surface, and right after a thorough cleanup. in the summer you can almost walk across the pond without getting your feet wet .

[RandyFolds]

That is a baller pond. Start the aquaculture op!

Not sure what you mean. If you think there is not enough plants in the water, keep in mind thats early spring before most of the plants and lillies surface, and right after a thorough cleanup. in the summer you can almost walk across the pond without getting your feet wet .

No, I meant you should be farming food fish and vegetables in there. 10,000g with some upgrades to the biofilters should be able to handle a good five or six thousand pounds of tilapia, easy...just cut out some raceways and start growing greens and herbs for your local restaurants.

[P4man]

So you are suggesting I replace my precious Koi with these hellish creatures:



No thanks. Its so ugly I wouldnt even want to eat it .

If I were in it for the money, I even think growing Koi is the better investment. Though I would need warmer water... (or indoor winter tanks).

[RandyFolds]

So you are suggesting I replace my precious Koi with these hellish creatures:

No thanks. Its so ugly I wouldnt even want to eat it .

If I were in it for the money, I even think growing Koi is the better investment. Though I would need warmer water... (or indoor winter tanks).

Oh, there are some prettier species than that but they are all pretty fugly in the grand scheme of things.

I only suggested tilapia cause it can tolerate the highest density. You could grow out some walleye pike or something awesome like that, but like all the other delicious apex predator fish, they are super cannibalistic and have like, 90% mortality on an ok run.

I know a couple people who culture Koi in California and make a good amount of money on it, but for every nice koi, there are a thousand flushers.

[P4man]

Ive been reading and searching further on this subject to decide on the oil. I can not find a cheap local source of mineral oil, so Im gonna go for vegetable oil. Im aware this is less stable and can oxidize (go rancid). It seems the biggest factors contributing to oxidation are sunlight and humidity. The first is easy enough to tackle, I have no need for a transparent aquarium, by setup is going to be butt ugly anyway.

To counter humidity, Im going to try to add a layer of mineral oil on top of the vegetable oil as sealant. Mineral oil is lighter and should therefore float on top, but Ill have to see if it mixes or not.

If anyone has other suggestions, Im all ears. Is there something lighter than mineral oil that is stable and not conductive to use as sealant?

[SgtSpike]

Ive been reading and searching further on this subject to decide on the oil. I can not find a cheap local source of mineral oil, so Im gonna go for vegetable oil. Im aware this is less stable and can oxidize (go rancid). It seems the biggest factors contributing to oxidation are sunlight and humidity. The first is easy enough to tackle, I have no need for a transparent aquarium, by setup is going to be butt ugly anyway.

To counter humidity, Im going to try to add a layer of mineral oil on top of the vegetable oil as sealant. Mineral oil is lighter and should therefore float on top, but Ill have to see if it mixes or not.

If anyone has other suggestions, Im all ears. Is there something lighter than mineral oil that is stable and not conductive to use as sealant?

I like this idea.  Way to think outside the box!

[P4man]

Its not so far out of the box, since I got the idea while reading about mineral oil often being used to seal other liquids. So why not vegetable oil
Anyway, Ill go shopping this weekend and Im buying some extra parts to build a rig around an old 8800GT to experiment with.

Some other points I came across:
- thermal grease will dissolve in oil. Before plunging in the cards, youlll have to remove all thermal grease. I hope the vrm pads will manage.
- I came across one report of overheating with a S775 CPUs, despite the oil being cool. apparently caused by air trapped in the socket; though Im not quite sure I understand how that would work, Im assuming this is not a problem with GPUs as there are no sockets.

[Defkin]

What about if you used a metal box like an ammo box that you can just fit the cards into. Leave the fans on the cards to circulate the oil. Because the cards fit snugly into the box not as much oil is needed to submerge them, this way you can use the mineral oil rather than run the risk of vegetable oil.

Place the metal box into a larger plastic container of water. Place it the top of the metal box is sitting above the top of the plastic container so any accidental water overflow goes onto the floor not into the box. Pump water into the plastic container and use gravity to take it back to the pond via an overflow. The oil/metal/water interface should be a good heat conductor.

Make sure you put a zinc in the water to stop galvanic series eating the box away.

I cannot see the issue about thermal grease being eaten away, if it was wouldn't just be replaced by the oil that ate it??

[P4man]

What about if you used a metal box like an ammo box that you can just fit the cards into. Leave the fans on the cards to circulate the oil. Because the cards fit snugly into the box not as much oil is needed to submerge them, this way you can use the mineral oil rather than run the risk of vegetable oil.

Place the metal box into a larger plastic container of water. Place it the top of the metal box is sitting above the top of the plastic container so any accidental water overflow goes onto the floor not into the box. Pump water into the plastic container and use gravity to take it back to the pond via an overflow. The oil/metal/water interface should be a good heat conductor.

Make sure you put a zinc in the water to stop galvanic series eating the box away.

While this may work, you effectively reduce the surface area for the thermal transfer to the size of the box. I suspect an oil cooler would have a larger surface area, and for my setup at least, its much easier to drop a cooler in my existent filters where I already have waterflow, than create a box and somehow circulate large amounts of water through there without overflowing it due to pump head. With gravity return that means HUGE pipes or low flow.  You would also risk a fair amount of water evaporating in a place where I dont want humidity, ie, in the shed where my rigs are.

The idea of an ammo box is excellent though.


Oh, and no zinc in the water. My Koi dont like it

I cannot see the issue about thermal grease being eaten away, if it was wouldn't just be replaced by the oil that ate it??

Yes, the problem is thermal grease can be conductive. You dont want it dissolved in the oil. But indeed, for temperatures it should not be a big concern as it would be replaced by oil.  To make sure no air gets trapped, you will want to smear some oil on the die before re-mounting the heatsink.

[Defkin]

I think you might be surprised how much heat a metal surface area can transfer with liquids on both sides. It would be easy enough to test if you have a submersible heater or jug element.

I am trying to picture what you are going to do. Are you only putting the cards into the pond if so how will you protect the MB and PSU etc?

[P4man]

I think you might be surprised how much heat a metal surface area can transfer with liquids on both sides.

Its no different than with a submerged radiator. Assuming your ammo box has equal thermal transfer characteristics as an oil cooler, which I doubt considering the thickness, coating etc, all that matter is surface area and temperature difference between the liquids.  A radiator has a huge surface area for its volume, while with your approach, surface area is directly linked to the amount of oil and scales rather poorly with it (cubic root) .

Mind you, Im not saying it wouldnt be enough but I fail to see the advantage, particularly since I wouldnt be able to flow nearly as much water through the "containing container", so Id have higher water temps (and evaporation).  The rigs will be above pond water level, so I cant use gravity feed, I need pump fed. Since you cant pressurize the container, you need gravity return. Unless I plumb at the very least 50mm water return pipes to the shed, thats going to be a serious limitation on flow rate or cause headaches with the water level. To give you an idea, I use 130mm return pipes in my filter, and with my pump capacity even that creates a 10+cm increase in water levels in the filters. Now I dont think youd need anything like the kind of waterflow I have through the filters, but it sure doesnt hurt, and I already have it, so why not use it? The higher the flow, the lower the water temps.

I am trying to picture what you are going to do. Are you only putting the cards into the pond if so how will you protect the MB and PSU etc?

Not sure what you mean by protect. Protect from what? Take a motherboard with a few gpu's (probably using extender cables), turn it upside down. Drop the cards in an oil bath. Even if oil would splash on the MB or PSUs or, or the oil creeps up, it doesnt matter. Ill probably prevent this by creating a lid over the oil box though, mostly to prevent dirt from getting in.  I will wire the cables through the lid and seal it (and may use PCIe power extender cables that are fixed in the lid, so the psu cables plug in to the lid), but thats not even necessary.


Here is sketch made by the 5 year old in me to explain :

[Defkin]

I think you might be surprised how much heat a metal surface area can transfer with liquids on both sides.

Its no different than with a submerged radiator. Assuming your ammo box has equal thermal transfer characteristics as an oil cooler, which I doubt considering the thickness, coating etc, all that matter is surface area and temperature difference between the liquids.  A radiator has a huge surface area for its volume, while with your approach, surface area is directly linked to the amount of oil and scales rather poorly with it (cubic root) .

Mind you, Im not saying it wouldnt be enough but I fail to see the advantage, particularly since I wouldnt be able to flow nearly as much water through the "containing container", so Id have higher water temps.  The rigs will be above pond water level, so I cant use gravity feed, I need pump fed. Since you cant pressurize the container, you need gravity return. Unless I plumb at the very least 50mm water return pipes to the shed, thats going to be a serious limitation on flow rate or cause headaches with the water level. To give you an idea, I use 130mm return pipes in my filter, and with my pump capacity even that creates a 10+cm increase in water levels in the filters. Now I dont think youd need anything like the kind of waterflow I have through the filters, but it sure doesnt hurt, and I already have it, so why not use it? The higher the flow, the lower the water temps.

I am trying to picture what you are going to do. Are you only putting the cards into the pond if so how will you protect the MB and PSU etc?

Not sure what you mean by protect. Protect from what? Take a motherboard with a few gpu's (probably using extender cables), turn it upside down. Drop the cards in an oil bath. Even if oil would splash on the MB or PSUs or, or the oil creeps up, it doesnt matter. Ill probably prevent this by creating a lid over the oil box though, mostly to prevent dirt from getting in.  I will wire the cables through the lid and seal it (and may use PCIe power extender cables that are fixed in the lid, so the psu cables plug in to the lid), but thats not even necessary.

Sorry I had this picture of a PC hanging from a tree (little birds nesting on it) GPUs hanging down from it into the pond......


Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

[P4man]

Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

I see no reason why that wouldnt work, but boy, sure sounds a lot more complicated than buying a $40 oil cooler. In either scenario you still need tubing, a pump, oil container etc. It would also take up even more space in my shed for no apparent advantage. Perhaps if you have a water source and no filter or pumps to use, then your approach might make sense, though Id probably still prefer to just put the radiator straight in the pond or swimming pool or whatever.

Also dont underestimate how difficult it is to make a pressurized vessel of any kind. Ive had a smallish commercial pressure filter once, with a 19mm in and outlet.
when I accidentally hooked up the wrong (too powerful) pump, it exploded. Water pressure is nasty.

[P4man]

I just did a small test, mixing vegetable oil with light paraffin oil; the parafin oil does float on top, but if you stir the fluids thoroughly, it seems to mix. An hour later I cant really say I see a layer of parafin oil floating on top. Bummer .

[jCole]

ever think of just keeping the side panel off when you run it?

[P4man]

ever think of just keeping the side panel off when you run it?

Lol. I might try that, if there were any side panels. Or top or bottom

[Defkin]

Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

I see no reason why that wouldnt work, but boy, sure sounds a lot more complicated than buying a $40 oil cooler. In either scenario you still need tubing, a pump, oil container etc. It would also take up even more space in my shed for no apparent advantage. Perhaps if you have a water source and no filter or pumps to use, then your approach might make sense, though Id probably still prefer to just put the radiator straight in the pond or swimming pool or whatever.

Also dont underestimate how difficult it is to make a pressurized vessel of any kind. Ive had a smallish commercial pressure filter once, with a 19mm in and outlet.
when I accidentally hooked up the wrong (too powerful) pump, it exploded. Water pressure is nasty.

I was under the impression you had the pump and water flow already (pond filter) needing only a 3/4 inch (garden hose) bypass setup 20-30 psi. As for the rest I guess I was looking at my shed, the drum and scrap is sitting there....although I would have made a purpose built heat exchanger out of the same junk pile.

Have you considered having a fridge evaporator submerged into the oil? More power used but better cooling/control. I have the vac and reclaim gear so maybe not an option if you don't have access.

in your diagram you have not shown how you planned to pump the oil to the oil cooler. Also missing is the number of gpu you need to drown i.e. min dimensions of oil container need to house the gpu.

As i see it your issue currently is the amount of oil required? What if you submerged the oil cooler in the oil and pumped the water though it. This would mean that the water side is an open loop and would need cleaning every so often....

 

[P4man]

Have you considered having a fridge evaporator submerged into the oil? More power used but better cooling/control. I have the vac and reclaim gear so maybe not an option if you don't have access.

No. Though I see no reason it wouldnt work, Id still be dumping the heat in the shed where I dont want it, and not in the water where at least it has some uses. Also I dont have a spare fridge and its very bulky and probably beyond my skills.

in your diagram you have not shown how you planned to pump the oil to the oil cooler. Also missing is the number of gpu you need to drown i.e. min dimensions of oil container need to house the gpu.

I would pump the oil with a ... pump . You could use most water pumps, if it can pump water, it can pump light oil. A large aquarium pump might do the job, but overheating is something to pay attention to. I dont know how hot the oil will end up being, but assuming 50+C, thats not something all pumps will like. So , Im looking at this pump:

http://www.ebay.co.uk/itm/High-temperature-100C-Water-Oil-Pump-w-speed-Control-/160526138814

As for the number of GPU's; I only have 5 atm, but I plan on expanding that in the coming months. Im waiting for HD 7xxx0 cards to go mainstream and hoping 5xxx cards will become cheap secondhand.  But for now, I started work on a small bath that will hold 4 or 5 gpus max. Depending on temps I get, I might scale that up, possible by "daisy chaining" several oil baths using the same single pump and radiator or add more if need be.

But I actually suspect the above pump combined with a car or motorcycle oil radiator will be overkill for 10 cards, it might handle 100+ cards. After all, the oil radiator on my bike is no bigger, its only air cooled and my bike produces 80+ KW of power. Granted not all of that heat is dumped in the oil, but much of it is.

But Ill only know for sure when I have tried.

As i see it your issue currently is the amount of oil required?

Its a concern yes, certainly if I wanted to use pure mineral oil. All I have found here is hideously expensive. If you live in the US, this would seem good and cheap:

http://www.amazon.com/Durvet-Mineral-Oil-1-Gal/dp/B000HHLUE6

Ive not found anything remotely that cheap here.

For vegetable oil, its not much of a concern, its really cheap, though it will also depends how long it will last before it needs replacement. If it ever needs replacement, who knows? I dont .

 Since the amount of oil would have no real impact on the temperature theoretically, I plan on minimizing the amount. Currently working on a small 25L prototype. When my extender cables and a spare motherboard+cpu combo arrive I will plunge in a single old nvidia card with no oil cooling just to see what happens. If it doesnt overheat with just a single ~100W, I may even keep that running for a few months  to see how the videocard, fans and the oil cope.

What if you submerged the oil cooler in the oil and pumped the water though it. This would mean that the water side is an open loop and would need cleaning every so often....

Pumping dirty pond water with leaves, needles, fish poop, gunk, algae and what have you through a radiator is asking for trouble. Its gonna clog in a matter of days, at most weeks. I see what happens in my filters, its not pretty.  

[DeathAndTaxes]

I wish you luck P4man.  Nobody has yet produced a oil cooled setup which is more cost effective than traditional water cooling but you access to a massive heat sink (pond) means you might be able to.

Your concept is the first that at least on paper makes me say "hmm" that might work.  The largest barrier is the high cost of mineral oil.  I almost wonder if some single GPU container would make sense.

To visualize.  Imagine a container (no top) which is roughly the size of a single graphics card.  If you have 4 GPU on  a board you set 4 of the containers side by side, turn MB upside down so the GPU are hanging into the 4 smaller containers.  Now you get a 4 way manifold and run 4 tubing lines to the 4 containers, opposite side of container has an outlet where 4 lines connect to a manifold again. 

A parallel cooling setup.  While more complicated if it saves you a gallons of mineral oil on each rig that savings could be worth it.  The large problem is graphics cards are "tall" (say 5").  If you have a large single pan (12" by 8") and you need to have 7" of depth you are talking 3 or 4 gallons. 

Some more "volume efficient design" (say 7" by 3" by 8") may allow you to use only half a gallon per card (plus amount in the loop).

You may still want to consider a heat exchanger if you need to pipe the cooling fluid a long way to the pond.  Having a short "oil loop" for each rig and then all rigs connected in parallel and then dumping that heat into a heat exchanger for a long range water loop to the pond would reduce the amount of oil you need. 

If cost of oil in long distance loop > cost of heat exchanger well you are golden.  A more expensive setup would be 1 heat exchanger for each rig connected to a single long distance water loop to the radiator in the pond.  The nice thing about using an exchanger is it would require 2 leaks to pollute your pond.

[P4man]

I almost wonder if some single GPU container would make sense.

or how about.... no container at all? I just saw this:

http://www.youtube.com/watch?v=okVPiYD7ny8

Thats nuts. He is not even using a heatsink on his Pentium4, just spraying the oil on it

You may still want to consider a heat exchanger if you need to pipe the cooling fluid a long way to the pond.  Having a short "oil loop" for each rig and then all rigs connected in parallel and then dumping that heat into a heat exchanger for a long range water loop to the pond would reduce the amount of oil you need.  

If cost of oil in long distance loop > cost of heat exchanger well you are golden.  A more expensive setup would be 1 heat exchanger for each rig connected to a single long distance water loop to the radiator in the pond.  The nice thing about using an exchanger is it would require 2 leaks to pollute your pond.

Hmmm... food for thought.  Though it would also require  a second pump doubling the potential points of failure and further increasing costs.
But if I go ahead with this, Ill almost certainly go with vegetable oil, and that makes the cost a non issue. Local supermarket sells frying oil for 1 euro per liter and its very liquid, almost water like. It might go bad in months, but I read people running their rigs in aquaria (so with light oxidizing the oil)  for 18 months without changing their vegetable oil, so who knows.

BTW, Im bidding on a Formula 1 transmission cooler that used to be in Michael Schumacher's Benetton LOL:
http://www.benl.ebay.be/itm/350525626493?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

3 days to go, Im sure it will go too high and Ill buy something more sensible but it would be fun

[Defkin]

http://www.petrochemcarless.com/white-oils.htm
I don't know where you live but you may want to try this place for the oil?


If I was going to build something like this here is what I would do assuming of course I had a pond

I would use a 240v recirculating pump (have it) and a car radiator (have it) and make the exchanger out of 10mm plate (have it). Only thing I would have to buy is the water hoses, steel pipe and the oil.
 

[P4man]

@Defkin
I dont have the metal working skills to make something like that work. I dont have any hand working skills really, so thats no surprise . I also think you have a lot of work to achieve relatively small heat exchange surface. And Id still be hesitant to pump pond water through it. All kinds of things are going to live in there and accumulate. Ever seen a string algae blossom?

@DnT and everyone
DnT gave me another idea with his "single gpu container" approach. Its too much work as he put it, but there is an easier alternative that achieves almost the same. Im thinking of making slightly oversized mockups of my videocards with some room for oil flow, position them in the PVC container, and fill it with polyurethane foam.  It will help keep the cards in place, drastically reduce the amount of oil I need, and can help directing the oil flow. I could also embed some tubing to deliver the cool oil right at the fan intakes and remove the oil at the exhausts. Its a bit of a hybrid approach between the video I linked above (splashing oil on the hot components) and DnTs suggestion.

Now Im not entirely sure if PUR foam will resist being submerged in oil for extended period of time. I fear it may not. I know water eats it away slowly (we are talking years, but still), so I may have to coat the hardened foam with something. I have some fiberglass and epoxy raisin I could use, though perhaps just coating it with some kind of oil resistant paint or sealant might be enough. Suggestions?

Im also wondering how to make the mockups and be able to remove them without tearing up the PUR foam. Or maybe I should just fill it with foam and carve out the areas with a dremel or something. Im not much of a handy man so suggestions are welcome

[DeathAndTaxes]

I don't think Defkin intended to use pond water in the "water loop" because his post indicated using a pump and radiator he has. 
So it would be oil box -> water loop -> radiator in pond

Also you likely don't need as much surface area as you think.  Remember air is an utterly horrible heat transfer mechanism.  Radiators have massive surface area because air is so friggin bad. 

Thermal conductivity:
Air 0.025 W/(m*K)
Mineral Oil 0.138 W/(m*K) <- 5x higher
Water 0.600 W/(m*K) <- 24x higher

The effective difference is actually much higher because air density is so low it takes a much larger fan/pump to move the same amount of material.

So radiators have such high surface area due to two properties of air:
a) moving a lot of air is difficult
b) air is such a poor conductor of heat

So for an equal amount of working fluid you could get away w/ 1/5th the surface area relative to an air-radiator design.  In reality you could get away with maybe 1/20th because you could simply pump working fluid faster.   As a practical example in those links I had above for heat exchanger are flat plate exchangers and they have much surface area than an air-radiator design.

[Defkin]

DnT has pretty much nailed it with what I was doing. Cutting and welding metal for me is easier to do than any other material such as wood and even cardboard for that mater. It is perfect for heat exchange, in fact most of the difficulty working with it is due to heat exchange. But as you don't have the skills or equipment.......being such a small simple job it might be worth getting the local workshop to do it but that would prob exceed your budget.


Anyhow back to the idea you and DnT were working on. How are you with fiberglass? I don't like it much because it is messy and makes me itch but it is probably ideal for individual covers and it is cheap. You can make a mold out of a block of wood and waxed paper.

Expanding or simplifying the idea DnT suggested you could make the containers and fiberglass them into a tray made from ply wood. Have small holes in the base of each container and flood the tray with oil. The oil will fill the containers and drain out of the holes. Adding a large hole on the tray at a higher level will allow you to crank the pump up until it goes down this overflow thus giving you a uniform flow of oil through each container.

The real beauty of this idea is that if you ever give up mining, with some seeds, hydroponic solution and a grow light you have a ready made indoor hydroponic system and a brand new hobby, lol

[P4man]

That more or less boils down to what I intend to make, except, I dont like so much air. Too much chance of dirt getting in the oil. So fill most of the air in your drawing with PU foam or similar, and replace the freeflowing oil with some inserted tubing and its roughly the same idea. Only I dont have to worry about the pump capacity to maintain levels.

Im okay with fibreglass btw. Its messy, but I love the stuff. But its not as easy as youd think to make it water (well, oil) tight. Ill experiment a bit tonight.

[iambaboon]

If you do it, please post a picture here as well:
https://bitcointalk.org/index.php?topic=7216.0

Me interested as well. One friend of mine tried submerging a power supply in oil, ended up heating the whole  bath because of no radiator.

[P4man]

I will. But dont hold your breath. Im really slow (and not even very thorough) when it comes to stuff like this

My current plan of action; make a mold of sorts in a PVC tub, that will keep me busy for a while; then fill it with vegetable oil, insert a single spare old ~100W nvidia gpu with no oil circulation or cooling (other than the gpu fan). See what happens. I want to see the difference between oil temperature and gpu temps. I want to see how fast the oil heats up, and if that is local heeat, close to the card or if the entire bath slowly heats up.

 If the oil gets hot but without causing the card to really overheat, that would be perfect and Ill keep it running for some time to see the effects on the oil, the card, and measure temperatures in various places in the oil bath. With low ambient temps and a fan if needed, I hope to get there. 70C or so oil temp would be perfect as a worst case test scenario.

[Defkin]

That more or less boils down to what I intend to make, except, I dont like so much air. Too much chance of dirt getting in the oil. So fill most of the air in your drawing with PU foam or similar, and replace the freeflowing oil with some inserted tubing and its roughly the same idea. Only I dont have to worry about the pump capacity to maintain levels.

Im okay with fibreglass btw. Its messy, but I love the stuff. But its not as easy as youd think to make it water (well, oil) tight. Ill experiment a bit tonight.

The tray only has to be big enough to accommodate the cards and a channel big enough to deliver oil to the containers and overflow. Even then you can eliminate most of the surface area by raising what parts you don't need above the oil level.
                                                               
The pump control is easy just put in a bypass, place a valved connection between inlet and outlet, adjust valve to regulate flow.

I don't have any probs making fiberglass waterproof, try thinning the resin with acetone.

With this design I would be wary of the fire hazard, it would be bad enough with fiberglass I wouldn't want to go near PU foam. You will need a fail-safe shutoff switch in case the oil pump stops, you can make a relativity bullet proof one out of a mirco switch and a syringe.

[P4man]

All oil is flammable, so Im not sure what risk the PU (or fibreglass) would add to that. If it catches fire, my shed will burn down anyway. But in case the pump fails, the cards will just shut down, and long before the oil reaches flash point.

Anyway, while I appreciate the thoughts and drawings, Ive pretty much made up my mind. Unless experimentation throws up some unexpected results, I will be using a single PVC container that will hold the cards (im building the first to hold 6 with 2 motherboards), pump, oil and PU foam (if needed, coated with something, perhaps just some oil resistant primer paint). The oil will be circulated to the radiator in my pond filter.  There is no risk in it running dry unless I have a leak, or overflowing, and its a fair bit easier to set up, not too mention more compact and easier to move.

Ive just filled a tiny plastic cup with PU foam and vegetable oil that I will keep an eye on to see if it breaks down. I suspect it will, but hopefully only in the very long run. Once hardened, PU is supposed to be pretty inert.

[DucRider]

I'm a bit of a motorcycle gearhead, so I'm really curious about repurposing a wrecked oil cooling system for laughs.

[P4man]

I'm a bit of a motorcycle gearhead, so I'm really curious about repurposing a wrecked oil cooling system for laughs.

I hear ya. Among others, I still got an old (oil cooled!) GSX750F in my garage. Its no longer in driving condition, been thinking about lending that oil cooler.  But  Im worried it might be corroded and contain lots of metal particles. Think its safer to buy something new.

[Defkin]

All oil is flammable, so Im not sure what risk the PU (or fibreglass) would add to that. If it catches fire, my shed will burn down anyway. But in case the pump fails, the cards will just shut down, and long before the oil reaches flash point.

I was not concerned about the oil directly in fact due to the high flash point of oil I would say it is likely to put out a fire.

Consider this, you have intermediate fuels in close proximity to the card, PU foam, plastic wire insulation, plastic moldings etc all nicely heated up by the card. If you lose the oil flow all those materials are now lightly coated in oil and with the splash method you might even have created an air-fuel mixture. Your ignition source would be the card, it has a lot of current running through it, a fatigued solder joint, poor connector or faulty component and there is your initial flame. Normally in an air cooled pc you would only expect get a brown spot on the PCB or a blackened connector, maybe not even that much with the oil running, without the oil running the risk of fire is considerably higher.


Anyhow good luck with the project and don't forget to post pictures when you get it up and running

[P4man]

Im bumping in to my first problem. PU is lighter than oil. It doesnt stick well enough to the PVC container, so it will float. I guess that can be worked around by mechanically forcing the block down, but its not a good start lol. On the bright side, its a joy to dremel canals and stuff in PU foam. If I didnt have 2 left hands, Id start sculpting!

[FlipPro]

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

[P4man]

This is about oil submersion.

[DeathAndTaxes]

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

People have nothing but problems w/ aircooling too.  Check mining troubleshooting thread.  I have a quad 5970 workstation water cooled for 2 years now.  Cold & Quiet 24/7.

[P4man]

Consider this, you have intermediate fuels in close proximity to the card, PU foam, plastic wire insulation, plastic moldings etc all nicely heated up by the card. If you lose the oil flow all those materials are now lightly coated in oil and with the splash method you might even have created an air-fuel mixture.

With my setup, a pump failure wont cause the card to run dry. The only real chance of running dry is when the oil leaks out in to my pond. I intend to install a floatswitch of sorts to shut the system off, possibly even close a valve, more to protect my pond than my shed . Even so, assuming oil cooling could manage to keep these cards around 50C, you could just define a shutdown point at 70C or whatever.  If there isnt a big difference between working oil cooling and no oil or static oil, then the whole exercise would be proven futile.

BTW, I also already have smoke detectors near my rigs. Of course that only helps if Im home. Still not a bad idea to grab one, they cost next to nothing.

[Defkin]

Im bumping in to my first problem. PU is lighter than oil. It doesnt stick well enough to the PVC container, so it will float. I guess that can be worked around by mechanically forcing the block down, but its not a good start lol. On the bright side, its a joy to dremel canals and stuff in PU foam. If I didnt have 2 left hands, Id start sculpting!

Maybe stick nails into the foam to weigh it down?
Have you tried plumbers glue?

[DeathAndTaxes]

Maybe stick nails into the foam to weigh it down?
Have you tried plumbers glue?

I like the idea of nails or maybe model weights over glue.  Who knows how well plumbers glue holds up over course of a year in hot oil.

[P4man]

Maybe stick nails into the foam to weigh it down?
Have you tried plumbers glue?

Good thinking. Would need a lot of nails but something like that should work. Or just rocks or bricks. Create a bottom layer of pu foam , then put whatever weight on it, then apply the next layers so its firmly embedded. Ill try that for V0.2 Now Ill just make some "bridges" in the PU that stick out above the PVC bowl and press it down with rubbers. Or something.

[P4man]

Progress report #1.

Pur foam dried out and I started cutting :



As you can see im very good at measuring and sawing straight lines



I also underestimated the size of these cards, so this will be a single motherboard, 4 card box.

The PUR foam will need some sort of coating, it will always keep giving off particles, that cant be good. 

[P4man]

BWAHAHAHA.. I won the auction on Michael Schumachers Benetton F1 oil radiator 

http://cgi.benl.ebay.be/ws/eBayISAPI.dll?ViewItem&item=350525626493&ssPageName=ADME:L:COSI:BE:1123

21 GBP.

ROFL. Im sure that will increase my hashrate by at least 10%!

I hope its not rusty or leaky, whoever sold it probably didnt expect anyone to actually want to use it LOL

[jake262144]

... I won the auction on Michael Schumachers Benetton F1 oil radiator...

Good for you P4

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

Buy the nonconductive coolant then.

[mxxx363]

I've seen some rigs in mineral oil before. 

Looks pretty sick when it's submersed in an aquarium.

[Fanatic]

Don't do it! This is madness!

[JusticeForYou]

I believe there are some CFC's that would work. Actually, so would 'pure' water.

However, wouldn't it be less risky to figure out the thermodynamics of the system and appropriately set your Freezer to the correct settings. 

[DeathAndTaxes]

... I won the auction on Michael Schumachers Benetton F1 oil radiator...

Good for you P4

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

Buy the nonconductive coolant then.

Garbage.  Distilled water is non-conductive (or more correctly has very low electrical conductivity).  Lots of horror stories of all that wonder goop breaking down inside waterblocks and destroying radiators.

Distilled water + silver kill coil + opqaue tubing (I swear by Tygon Silver medical grade tubing).  You don't need anything else. 

Of course distilled water is boring so companies sell ULRTA SUPER QUANTUM WATER NOW W/ 82% MORE MOLECULAR COHESION AND LEET NANOPARTICLES!!!!

[P4man]

I believe there are some CFC's that would work. Actually, so would 'pure' water.

CFCs? Only CFCs I know are gasses (at room temperature) and many of them powerful solvents. Aside from the fact they are illegal in most places, sounds like a terrible idea. Almost as bad as "pure" water that will ionize within the hour and short everything out.

However, wouldn't it be less risky to figure out the thermodynamics of the system and appropriately set your Freezer to the correct settings. 

If you dont mind more than doubling power consumption, coping with condensation and be able to move the heat to where you want it, yeah sure.

[jake262144]

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

Buy the nonconductive coolant then.

Garbage.  Distilled water is non-conductive (or more correctly has very low electrical conductivity).  Lots of horror stories of all that wonder goop breaking down inside waterblocks and destroying radiators.

DAT, I targeted that piece of advice at a guy apparently having issues with his WC installation. Distilled water rocks but if you have even a minor leakage, it will pick up dirt and the conductivity rises fast. In this context, going with chemical coolants might not be that bad an idea, huh?
I'm not advocating that stuff over good-old water for general use, neither am I not trying to change your opinion.
I'm trying to find an optimal solution to a specific problem so that a newb operator doesn't burn his rig down.
You're right though - if the installation finally proves watertight and runs without problems, you can easily replace the chemicals with water.

[P4man]

How about mineral oil? Its not like those watercooling tanks take 10 gallon, so cost isnt a big concern. Of course it would reduce flow rate a bit, depending how viscose the oil is, but Im unsure if that would be a problem. At most upgrade the pump. Im sure someone has tried this, anyone seen results?

[DeathAndTaxes]

Don't do it. I have a sli watercooled 6990s and its been nothing but problems. Running water and electronics non stop is not a good combination!

Buy the nonconductive coolant then.

Garbage.  Distilled water is non-conductive (or more correctly has very low electrical conductivity).  Lots of horror stories of all that wonder goop breaking down inside waterblocks and destroying radiators.

DAT, I targeted that piece of advice at a guy apparently having issues with his WC installation. Distilled water rocks but if you have even a minor leakage, it will pick up dirt and the conductivity rises fast. In this context, going with chemical coolants might not be that bad an idea, huh?

No because those chemical coolants are mostly distilled water and thus have the same "issue".  There are coolants which remain non-conductive but they tend to run $100+ a gallon and they tend not to come in "ultra leet" packaging.  

Not one of those "super goop" coolants makes any claim that they are less conductive than distilled water or will remain non-conductive when exposed to contaminants.  Reread the product description.  They don't provide better cooling, they don't provide better anti-fungal protection, they don't provide corrosion resistance on an all copper system, and they don't provide electrical protection.  Pure snake oil in a bottle marked up a couple thousand percent. 

I haven't seen one post EVER where any of that "super goop" helped a system but I have seen many horror stories of the stuff breaking down, leaving deposits, and "gooping" up components.

Water works.  It is used to cool super computers.  Plain distilled water.

[DeathAndTaxes]

How about mineral oil? Its not like those watercooling tanks take 10 gallon, so cost isnt a big concern. Of course it would reduce flow rate a bit, depending how viscose the oil is, but Im unsure if that would be a problem. At most upgrade the pump. Im sure someone has tried this, anyone seen results?

You probably could but you lose a lot of cooling capacity, need a much beefier pump and all the components essentially have no resale value once contaminated with oil.  The main advantage of submersion cooling with oil is that you don't need expensive water blocks (5970 full coverage blocks are $120 each).  To combine expensive watercooling gear w/ expensive oil seems ... well expensive.

Honestly if built right with good quality compression fitting leaks during operation are rare.  
1) Buy high quality tubing.  Not the ultra gamer UV super cool junk.  Get tubing used for industrial purposes (where people buy stuff that works) like Tygon.
2) Buy good compression fittings.
3) Don't use any "goop".  Distilled water + opaque tubing + silver kill coil = clear water for a long time.
4) Change out the water every 12 months.
4) Once built, LEAVE SYSTEM POWERED OFF, jumpstart the PSU to run just the pumps for 24 hours and bleed the system.

If you change components, go through a powered off leak test for 24 hours again.  I have had 3 leaks.   I have damaged no systems by watercooling.  Over the years I have blown HDD, video cards, power supplies, one AMD CPU that had a fan which siezed but never from water cooling.  

[jake262144]

You are right DAT⁽¹⁾. On close inspection it appears I have taken that liquid for more than it actually is.
Thanks for kindly bringing this issue to my attention.

As much as I agree with doing extensive bleed testing of the assembled system, I'm afraid newbs will keep doing the newbish thing and run the machine ASAP :/
The same with security - some subjects which seem too complicated (or just non-intuitive) will constantly be overlooked.

Notes:
(1) As always, dang it

[RandyFolds]

You are right DAT⁽¹⁾. On close inspection it appears I have taken that liquid for more than it actually is.
Thanks for kindly bringing this issue to my attention.

As much as I agree with doing extensive bleed testing of the assembled system, I'm afraid newbs will keep doing the newbish thing and run the machine ASAP :/
The same with security - some subjects which seem too complicated (or just non-intuitive) will constantly be overlooked.

Notes:
(1) As always, dang it

But it guarantees exact volume by European Standards!

[DeathAndTaxes]

On close inspection it appears I have taken that liquid for more than it actually is.

No problem.  Don't feel bad they sell a lot of that crud each year.

Sometimes it ends badly:

http://www.xtremesystems.org/forums/showthread.php?226632-Confirmed-Feser-1-Blue-Premix-GTZ-do-NOT-want&p=3837299#post3837299



The rig owner is a long time watercooler and folding @ home user.  He believes folding 24/7 cause thermal dissociation of the coolant compounds. 

Hmm.  running chips extremely hot continually for months at a time.  That reminds me of some similar activity.

Distilled water + kill coil + good quality (Tygon) opaque tubing.

[P4man]

PCIe extenders arrived yesterday and my "Michael Schumacher" oil radiator arrived this morning.
I should have read the specs more carefully, it clearly said 18.5cm so I only have myself to blame, but holding it in my hand, that is MUCH smaller than I thought by looking at the photograph.  Its exactly the size 2 90mm fans next to each other, so smaller (but thicker) than your typical highend PC watercooling radiator.  Somehow I pictured it at least twice that size.

Still, with its relative thickness and extremely fine grating and Im sure its more than capable of dissipating the heat of a few gpus, at least when submerged in cool water. Its actually kinda neat, and I cant believe how light it is. It came with a certificate of authenticity too, so thats at least an extra 100 MH/s .

I also picked up the cheapest 1200L/H aquarium pump I could find (15 euro). I dont expect it to last, Im sure it will overheat and fail,  I just want to see what happens regarding flow rate and temperatures when it must pump oil so I get a rough idea of sizing the actual pump. 1200 L/H turns out to be a serious amount of water for such a tiny pump, wow,  but then it doesnt have to cope with thicker oil yet, nor any resistance from long tubes and the radiator, so we'll see what that gives.

Now Im waiting for some epoxy raisin to arrive to coat the foam, I need to pick up some tubing and with some luck Ill have a test setup running this weekend, although it will be "dry" for now, cooling the oil with just fans. Its freezing -11C outside, so my pond pumps are shut down. Should the oil heat up too much (which I highly doubt) I can always submerge the radiator in a bucket of water for testing.

question: have any watercooling guys here measured water temperatures at the inlet and outlet of their radiator? Can you give me a ball park guestimate?

[P4man]

Distilled water + kill coil + good quality (Tygon) opaque tubing.

Ive never done any water cooling, but if you are worried about algae, you could use an UV-C bulb.  Its perfect to avoid green water.

[DeathAndTaxes]

Distilled water + kill coil + good quality (Tygon) opaque tubing.

Ive never done any water cooling, but if you are worried about algae, you could use an UV-C bulb.  Its perfect to avoid green water.

Yeah that certainly is an option especially if you have a clear tank.  Still I have found using opaque tubing makes the environment inhospitable.  That combined w/ tubing like Medical grade Tygon Silver (which has silver ions) is a semi-permanent bacteriacide.  Adding silver kill coil in the tank is really just being over cautious but it is cheap insurance.

Algae needs light and opaque tubing removes that.  No algae & no bacteria = no food for larger micro organisms.  Still if I ever had a problem I would look into a UV-C light aimed at the tank (or simply taping up the tank so it is opaque) before I put any "super goop" in my system.

IBM makes water cooled servers I wonder if they run straight distilled water or what they add.  I would imagine for something as large as super computer making a mesh of silver that could be installed/replaced in the loop would improve surface area contact with the water.

[DeathAndTaxes]

PCIe extenders arrived yesterday and my "Michael Schumacher" oil radiator arrived this morning.
I should have read the specs more carefully, it clearly said 18.5cm so I only have myself to blame, but holding it in my hand, that is MUCH smaller than I thought by looking at the photograph.  Its exactly the size 2 90mm fans next to each other, so smaller (but thicker) than your typical highend PC watercooling radiator.  Somehow I pictured it at least twice that size.

Still, with its relative thickness and extremely fine grating and Im sure its more than capable of dissipating the heat of a few gpus, at least when submerged in cool water. Its actually kinda neat, and I cant believe how light it is. It came with a certificate of authenticity too, so thats at least an extra 100 MH/s .

I think you are fine.  Remember water has 20x the thermal conductivity as air.  Granted it works slightly different than a flat plate heat exchanger but @ roughly 2gpm and a 20C delta (cold loop 20C colder than hot loop) a flat plate heat exchanger can dissipate over 5KW of thermal load.

question: have any watercooling guys here measured water temperatures at the inlet and outlet of their radiator? Can you give me a ball park guestimate?

Measuring temp in the loop isn't really practical.  Water has such high thermal conductivity that the whole loop roughly reaches equilibrium.  Every point in the loop (inside GPU water block, right before radiator, right after, inside radiation, inside tube) are all within 2-3C of each other.

So just look at GPU temps and you are fine.  From that you can assume every point in the loop is within 2-3C of that.  Granted oil has lower thermal conductivity but it is closer to water than air.  The reason why the "outlet" of a air cooled GPU is much higher than the inlet is because air has such poor thermal conductivity and you simply can't push enough air to keep the temp stable (it would require tens of thousands of cfm).

As far as "what temp".  In watercooling temps 20C over ambient air are considered the minimum.  If you aren't achieving that likely your system is undersized or you have some other flaw (cooling fluid bypassing hottest part of GPU, non-turbulent flow, etc).  <10C over ambient is decent.  <5C over ambient is really only useful goal if pushing CPU (which handle heat worse than GPU) to extreme overclocks.  <2C over ambient is possible but really provides just bragging rights.  You will always have some delta over ambient simply because the system has some inefficiency.  At best the radiator can only cool the oil to the temp of the cool side (air for you right now) and depending on flow rate, and size of loop the temp in GPU will rise some over that.

[outsidefactor]

Hey all! Interesting thread.

I saw an immersed rig at a LAN party recently. The guy had put water blocks on the CPU and GPUs and pumps that would handle the more viscous oil. The rig was fully immersed, the pumps then pushed oil into the water blocks and then out to a radiator and then just back into the tank, ready to circulate again and be picked up by the pumps again. Worked really well, and kept every component at about 2 degrees above ambient, even though it was significantly overclocked.

He said his next version was going to be built into a chest freezer. Madness?!?

[Defkin]

Grats on the oil cooler


My practical experience is on the multimillion dollar stuff and on the operational/maintenance side rather than design but the basic principles still apply. 

Your basic 'rule of thumb' is that you will achieve a 6 Deg C split between supply and return providing you are within your systems heat rejection capabilities. This temp split is a good indicator on the amount of heat rejection your system is doing.

For example:
If you are at 6 deg split and temp is still rising you have exceeded your capacity.
If you are at 6 and temp is falling you are at within your capacity.
If you are less than 6 and temp is stable the split temp you are at is a good indicator of your overall capacity at that heat load.
If you are less than 6 and temp is rising something is wrong.