Acceptable mining/ambient temperatures

[Witrebel]

I am trying to work through the logistics of setting up a medium-large sized farm.

I would like to think I have at least a rudimentary understanding of heat transfer. 

What I lack is a good understanding of how hot the equipment gets and what is acceptable. 

So I have a couple questions:

1) How hot do miners get under "typical" conditions.  I.e. not under or overclocked/volted, no extreme cooling systems.   
I understand that there is variance between each type of chip and each miner, im looking for "safe" numbers that apply to "all" hardware.

2) How hot can/have you continuously and safely run miners?
I get the feeling that with some hardware, the efficiency is directly coupled to the temperature, this is not important to me.  I simply want to know something along the lines of "at 65 deg C your miners will run forever, at 70 deg C your miners will run for at least a year, at 80 deg C your miners will most likely crap the bed in a month"

3) What are the upper limits of ambient temperatures you would imagine operating in? This strikes me as a function of the difference between your desired board temps and the ambient temp, coupled with how much fresh air you can pull through your miners. For example, if you had REALLY good circulation, pulling the exhaust heat out, and pulling a considerable amount of fresh "cool" ambient air through your miners, could you run them in 100deg F ambients?

[-ck]

Every single piece of hardware is completely different in terms of tolerance and where the temperature sensors on each device are (if they do exist) is also different, so absolutely no rule can be universally applied to all hardware.

[Witrebel]

That's fair.  However, the "worst case" miner would cover all possible scenarios, albeit with a much greater factor of safety than might be necessary for the more heat tolerant miners.  I am just looking for some good ballpark numbers to work up the baseline logistics of running a mining farm in a hot and humid climate.

To help me get there, at a minimum, it would be great to know if anyone has any luck direct air cooling miners with 100deg ambient temps.   

Any numbers or advice given will obviously be taken with a grain of salt and hopefully would come with some context.

[notlist3d]

That's fair.  However, the "worst case" miner would cover all possible scenarios, albeit with a much greater factor of safety than might be necessary for the more heat tolerant miners.  I am just looking for some good ballpark numbers to work up the baseline logistics of running a mining farm in a hot and humid climate.

To help me get there, at a minimum, it would be great to know if anyone has any luck direct air cooling miners with 100deg ambient temps.   

Any numbers or advice given will obviously be taken with a grain of salt and hopefully would come with some context.

CK gave you a perfect anwser.  There just is not one fits all.  Each model has it's own personality.

What brand/model are you looking at?  You need to narrow it from all miners to model.

[MCHouston]

Some models can handle 100F ambient, some can not, some hash less, some have hardware errors.

What miner are you buying?

[QuintLeo]

And some you have to downclock when the temperature is too high.

 Seems like most of the "big" farms I've seen actual pictures from go with "lots of airflow at ambient" though, since it's a lot less expen$ive than paying the 20-30% more electric to use A/C to keep things cool, and just put up with having to downclock/undervolt (as applicable) during the summer. It's also a reason a lot of the REALLY big farms are being built in cool areas, when they can find cheap electric AND cool ambient temperatures (like Iceland or some parts of Scandinavia).

[NotFuzzyWarm]

I am running most of my farm at ambient temps up to 93F (33.8C). Am running S2, S3, S3+, S4 and S5's there. All run perfect at stock speeds. Some S5's I've boosted to run @ 375MHz and they are still happy. Typical temps with 85F (29.4C) ambient range from low to mid 40'sC for the S3 family and around 55-65C for the S5's. At the 93F ambient temps go up less than 10C giving the hottest S5's temps around 72-75C.

[tennozer]

I am running most of my farm at ambient temps up to 93F (33.8C). Am running S2, S3, S3+, S4 and S5's there. All run perfect at stock speeds. Some S5's I've boosted to run @ 375MHz and they are still happy. Typical temps with 85F (29.4C) ambient range from low to mid 40'sC for the S3 family and around 55-65C for the S5's. At the 93F ambient temps go up less than 10C giving the hottest S5's temps around 72-75C.

Do you have any extra air condition device in your mining room? Stock speed with theses temperature look likes good.

[NotFuzzyWarm]

I am running most of my farm at ambient temps up to 93F (33.8C). Am running S2, S3, S3+, S4 and S5's there. All run perfect at stock speeds. Some S5's I've boosted to run @ 375MHz and they are still happy. Typical temps with 85F (29.4C) ambient range from low to mid 40'sC for the S3 family and around 55-65C for the S5's. At the 93F ambient temps go up less than 10C giving the hottest S5's temps around 72-75C.

Do you have any extra air condition device in your mining room? Stock speed with theses temperature look likes good.

No AC. Just moving enough outside air through the room to keep temp to the low 90's.

[QuintLeo]

We had some mid-to-high 90s around here a week or so back. I had to downclock the S5s 'cause I'm not willing to let them excede 60C (well, I'll fudge and put up with 61-62 for an hour or two at a time if I'm at work and can't adjust them exactly). Seems like the ambient has to go over about 80 before I got to that point though, and I didn't have to downclock them a lot even in the mid-90s ambient (lowest unit I think I dropped to 325 Mhz or so from the stock 350 Mhz).

 My SP20 didn't even notice, but I've got it undervolted anyway for better efficiency (I have high electric rates 'till mid-Sept).

 No AC. 3 room fans (each in a seperate window on the downwind side of my place) on thermostats sucking air into my place through 20"x20" furnace filters (15"x24" on one window 'cause that's what fits in that window), and a couple of those "windstorm" pair-of-smallish window fans on the output window more to be sure the rain don't come in when the wind is blowing the wrong way than for any other reason.

[Witrebel]

Thank you for the feedback everyone.  I appreciate it and I do understand that I am asking a VERY general question with no perfect answer.

I am working with a friend to mine in Venezuela.  For proof of concept I am renting a condo and running about 10TH in that space.  In this setup, it is direct air cooled in a closed space.  AC 24/7, consuming about 30% of the 70amp service to the room.  When I aggregate all monthly expenses into one single "hosting" cost per kwh, its like 3 cents.  

I can either rent more and more condos and fill them out, or I can scale up to an industrial space.  I prefer the later.

My focus is on something I can build and design myself. I am considering 4 cooling options.  Direct air cooling with high CFM using pure ambient, air cooling through some form of swamp cooling, air cooling with AC augmentation, and immersion cooling in mineral/corn oil, with a liquid liquid heat exchanger to remove waste heat.

Lacking a significant amount of capital, I want to put all my money into switch gear, power supplies, and miners.  So buying a 40 ton AC unit doesn't appeal to me.  This isn't cost prohibitive long term though, as power is down around 0.0002 USD/kwh, so a 40ton AC would cost like $20 a month to run.  I just don't have that kinda cash to splash on infrastructure.

Immersion cooling really appeals to me, I could weld up heat exchangers with 50 gal drums and aluminum pipes, but I have alot of research to do on cheap oils that have the right electrical properties for safe immersion of electronics.  I have a feeling it will still be cost prohibitive due to the shear volume of oil I would need.  

With 60-80% RH year round, swamp cooling isn't very effective, although it may be enough to keep temps between 80-90f which sounds like a workable solution.  

So using large air handlers and pulling huge amounts of airflow through the space seems like the most cost effective option.  I can build the structure from the ground up with the proper layout for this application. 

Needing to downclock/undervolt according to temperature seems like a non trivial task at the scale I hope to be running.  

Ideally I would be running S3's and S5's,  but frankly I will be running whatever I can source at the right price $/GH.  

[NotFuzzyWarm]

Hmm. At the electric price you pay AC augmentation is not a bad idea. As I've mentioned elsewhere we don't care about 'livable' temps for people. If ya can keep the miners input air temps below 93F, maybe 95F you are golden. Just put the cold side of the AC in the air input stream and kick in as needed. If they are packaged stand-alone, then again just make sure they feed the miner air input side and are not just blowing in the general room.

Biggest thing about just sucking in outside air to pressurize the rooms is to make sure it is filtered. Gotta keep out as much general dust and dirt as possible. Usually standard large home/commerical air filters are a nice fit to many fans and certainly simple blower (better) systems.

So using large air handlers and pulling huge amounts of airflow through the space seems like the most cost effective option.  I can build the structure from the ground up with the proper layout for this application. 

Ja. Just be sure to pay attention to the hot-aisle/equipment (miners)/cold-aisle concept to make the air streams don't mix (too much).

[Witrebel]

Hmm. At the electric price you pay AC augmentation is not a bad idea. As I've mentioned elsewhere we don't care about 'livable' temps for people. If ya can keep the miners input air temps below 93F, maybe 95F you are golden. Just put the cold side of the AC in the air input stream and kick in as needed. If they are packaged stand-alone, then again just make sure they feed the miner air input side and are not just blowing in the general room.

Biggest thing about just sucking in outside air to pressurize the rooms is to make sure it is filtered. Gotta keep out as much general dust and dirt as possible. Usually standard large home/commerical air filters are a nice fit to many fans and certainly simple blower (better) systems.

So using large air handlers and pulling huge amounts of airflow through the space seems like the most cost effective option.  I can build the structure from the ground up with the proper layout for this application. 

Ja. Just be sure to pay attention to the hot-aisle/equipment (miners)/cold-aisle concept to make the air streams don't mix (too much).

Thanks for the input.  I need to work out some of the physics involved, but if low to mid 90's are acceptable input temps, I really think I could make some form of evaporative cooling work.   And even if not, like you said an AC augmentation system as a backup could be used to mitigate the highs.

Regarding layout, I envision a basic system involving sections set up with a simple two isle mining configuration.  Hot isle in the center, exhaust fans overhead in the middle, filter pads in the exterior walls, a plenum for AC augmentation/evap cooling, feeding each cold isle on the outside.  Passive intake driven by the negative pressure from exhaust fans pulling on the hot isle. Screw it, ill draw it up in paint:

[NotFuzzyWarm]

Perfect and spot on. You have done this before I take it?
The nice thing about large swamp coolers (factory size) is that they are inherently excellent filters as well

[Witrebel]

Perfect and spot on. You have done this before I take it?
The nice thing about large swamp coolers (factory size) is that they are inherently excellent filters as well

Nope, the extent of my mining experience is setting up 3 ASICMiner tubes and running them for about 48 hours before shipping them off to Venezuala to be set up in a condo.  The should be coming online in the next couple of weeks.  I will be heading down to Venezuela mid November to set up an additional 7.5th of hardware in person and show my friend what is involved in maintaining things/setting up a full apartment.  For now she is on board with the idea of running multiple apartments, but I hope to have a viable business plan by that time so that we can discuss scaling up to an industrial level when I am there in person. I do have a degree in electrical and mechanical engineering which helps.

[QuintLeo]

Positive pressure works a LOT better when trying to keep the air filtered, otherwise you're sucking in dust and such from every hole in your location, NOT just through the filters.

 Swamp cooling in 60%+ relative humidity is almost ineffective, waste of time don't bother with it.

 At your electric cost I'd just bite the bullet and go standard A/C - you don't HAVE to do one huge unit at a time with it, do it incrimentally as you add mining capasity. You also don't need airflow THROUGH the building if you're using enough A/C to keep the temps cool - the "mass airflow" option is for a setup that does NOT use A/C to keep temps down TO ambient despite the heat input from the miners.

 I don't think ANY current miners are set up for immersion cooling, and it's a royal pain to deal with unless your gear is specifically designed for it.
 There used to be one WATER-cooler miner out there (Bitmain Antminer C1) but I don't think it's still in production and it's a bit dated on mining chip tech anyway. Might be able to find those used though.
 It's possible to set up other miners as water-cooled, which would work well if you can dig a big geothermal-type "loop" to run the cooling water through. Still need some air cooling though for the passive components and whatever you CAN'T attach water blocks to, but that's relatively small amounts of air cooling if you can get the mining chips themselves ALL water cooled. Works better on gear that uses "big" mining chips in small numbers, like Spondoolie Rockerbock-based stuff (SP20 etc) or KnC.

[Witrebel]

Interesting take on the positive pressure aspect. The dust aspect of negative pressure is certainly a consideration.  As far as I know, when flowing air through a heatsink enclosed in a tube (e.g. a miner), negative pressure works better than positive as it promotes better airflow.  But since each miner has its own fan, I would imagine having positive pressure overall in the building does not stop a miner from using its own fan to pull a local low pressure zone in the heatsink.  I think this may be worth modeling up in an a flow/heat transfer simulation. 

Regarding swamp cooling being ineffective, I have no dreams of getting it down to 70 deg F or anything.  What I would like to investigate, is can I use some massive scale DIY evaporative cooling media, like wood chips or something, wall to wall, to keep incoming air temps around 90 deg F, WITHOUT any AC.  But having some AC for augmentation makes alot of sense too, just have to design the flow rates correctly.

As for immersion cooling, it's a fringe idea, but one I am definitely going to investigate. I don't want to do water blocks.  I just want to find some commercially available oil with the right dielectric properties that resists ionization. Short of that, I would probably strip down miners into bare blades, and pursue waterproofing them for immersion in straight tap water.  Yes it is a PITA, yes it has a lot of kinks to work out, but I feel it may be a viable way to increase the density and thus profit margin of older equipment, or even maximize the profits on newer equipment via overclocking.