Bitcoin Forum
October 27, 2020, 12:34:20 AM *
News: Latest Bitcoin Core release: 0.20.0 [Torrent]
 
  Home Help Search Login Register More  
  Show Posts
Pages: « 1 2 3 4 5 6 7 8 9 10 [11] 12 13 14 15 16 17 18 19 20 21 22 23 24 »
201  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: April 27, 2016, 03:24:47 AM
Thanks, that's info I (a non-fab chip guy) can sink my teeth into.


... it would be better to cooperate with a IC design service company at least for the first project. You bring the chip concept and architecture, they help you to design, manufacture, package and test it.

Recommendations of companies that have experience in BTC chip design?

From my point of view, it is almost impossible to build up the required competences from scratch, despite you hire some experienced IC designers in your company.

Had a hunch that chip fab was a "black art" with few knowledgeable participants.
We cannot support a $500K budget for tools much less the employee expense to operate said tools.

Where is your company located?

North Central US (North Central Minnesota, near Leech Lake to put a finer point on it).

Considering the ~$1,000 per die prototype expense, the packaging seems cheap.

Is there any advantage to not packaging the prototypes?
202  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: April 24, 2016, 12:04:31 PM
Since it's obvious I couldn't find my ass with a map in the chip fab world, how about clarifying a couple of things:

50 prototype dies, unpackaged, untested

"unpackaged" means the bare die with no carrier? right?

48,000EUR for up to 3mm2 plus 16,000EUR per each additional mm2.

"3mm2" is the die size?

What is "... the required CAD/toolchain" to design (tape out?) something like sidehack was proposing?

We, as a company, have a couple of other chip concepts outside the crypto currency world.
If the cost of the S/W isn't to prohibitive and we knew what we were looking for/pricing we might spring for it.

Thanks in advance.
203  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: April 23, 2016, 03:56:14 PM
Number 1 is out, mostly for the reason that in order to not feel like I was screwing people over I'd have to sell miners pretty much at cost, and that doesn't keep me in business.
Number 2 is out because I've tried to raid an S7 and it sucks. Those heatsinks are hard to get off without wrecking the chip, and the chip itself is 0.4mm pin pitch which sucks to work with.
Numbers 3 and 4 are less distasteful but also less likely. Number 3 wouldn't be too bad as long as the people running the place had clear job descriptions and the authority to do their jobs thoroughly - managers do the paperwork and don't screw up the engineers, and engineers have the final say on design. Both sides are essential, but another thing that's essential is not sitting around for a friggin' year with thumbs up butts talking about things that don't matter instead of designing and prototyping a quality product and getting it to market. I like to think about Lockheed back during WW2, when they were asked to design and build a jet fighter (completely from scratch) and deliver a working model within nine months - a task many considered impossible - and they rolled it out ahead of schedule. That's the kind of stuff that can happen when people are allowed to do their jobs without interference.
Another problem is it takes an awful lot of money.

Fabb'ing a chip to tape out (in qty's of 250,000 minimum) is about 2 million. Don't see that happening anytime soon.
204  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: April 23, 2016, 10:06:28 AM
$13 per chip is about twice what it should be.

$13/chip is ~$10/chip over the cost to develop, manufacture, fabricate.
It's typical to ~double the cost to produce a product in setting a MSRP.
By my math, they ought to be around ~$6-$7 each, in any quantity.

These estimates are valid for the first production run.
Follow on production runs have no or significantly reduced embedded RD&D costs, so the price should drop, slightly.
To say $5-$6 /  chip.

Likely there are several reasons supporting the $13/chip MSRP:
1) They are the "only game in town",
2) There are significant benefits from an accounting standpoint for chips used internally priced at $13/chip,
3) Provides justification to "discount" chips supplied to other larger-ish board producers if sales to the community project are charged $13/chip,
4) and lastly, companies are in the business to make money. Maximizing that benefits shareholders. Upper level management reports to and maintains employment from the board of directors. If it came to light that profits were not maximized on a given product line that "official" would be eligible for termination.

As I see it, the community project has 4 choices:
1) "Bite the bullet" and pay the $13/chip,
2) Buy a bunch of S7's, rape the chips off the boards, and let sidehack work his magic on/with efficient board design,
3) A group of community members could band together and create AM version 2, fab a chip (BE400 Huh) and then produce boards/machines based off that chip,
4) lastly and least likely, a crowd funded community effort to produce a community chip sold at or near cost.

Personally, I like none of the above, for a variety of reasons.
205  Bitcoin / Hardware / Re: Community Miner Design Discussion on: April 19, 2016, 11:34:31 AM
Repeating the question. It looks like some prototype PCBs I ordered should be in next week. I can write enough code to get basic functionality but probably not actual mining, at least not within the schedule I have (what with manufacturing a new batch of PSU boards and a new batch of Compacs on top of regular duties). So, is anyone interested in working on a cgminer driver for a small project of mine and possibly sticking around to work on the base driver for the Open Community Miner core project?

In case you're wondering, I'm not assuming volunteers. I can't offer much right now but you would get paid.

Am interested.
The last serious coding I did was back in '94 (assembly, C, C++).
Have done some casual embedded coding in the interim.
My "compadre in crime" is well versed in the modern languages.
Have emailed him to see if he's interested/has the time.

Haven't looked at the cgminer source.
What languages are used and what language(s) expertise are you looking for?

We might be able to help.

Me = admin@planetcrypto.com
cc = support@planetcrypto.com

206  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 13, 2016, 07:58:18 AM

So is paying endlessly increasing (due to rate increases) electrical bills.

Where I am, my electrical coop(s) are real crooks. They managed to get into law a requirement for the owner to have a liability insurance policy. The cost of the policy exceeds even the maximum revenue stream for selling power back (+ net excess generation metering) as an IPP (Independent Power Producer 40 KW nameplate capacity or less) under the Minnesota Statute. If you exceed 40Kw nameplate capacity generation you're classified just as they are and have to negotiate a contract, typically at the "avoided cost rate". Which is the lowest priced rate class, and here, about $0.005 per Kwh (That's 1/2 cent per Kwh). They sell regular service power to the retail customer @ $0.1235. Hence my crook comment.

I decided long ago (1999) that it would be a cold day in Hell and the little devils would go skating when they got 1 miliwatt from me. F'em if they can't take a joke.

Oh, and yes, I have a sizable battery bank of U.S, Battery L16HC XC2's (20 Hour Rate: 420) and ~150 lbs each. The first batch of these wore out after 10 years of service, I abused them, else I'd a got 15 years out them. http://usbattery.com/products/6-volt-batteries/us-l16hc-xc2/ Best "bang-for-the-buck".

To avoid the insurance cost, I run a "hybrid" system. Solar charges the batteries (and a little AirX, which is really just a toy comparatively). If the solar charging system comes up short for the day, I have a Morningstar relay driver that senses battery voltage and turns on some high current (100A each) RV power converters (battery chargers http://www.amazon.com/gp/product/B00F8MC45E?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00) feed by off peak power ($0.048 per Kwh) at night. At 8:30 AM it turns them off in preparation for another solar charging day. This is by far cheaper than running a gas/diesel fueled generator (and a hell of a lot quieter) for "make up" power/charging. The size of the bill at the end of each month is indicative of how "sun shiny" the month was. After 17 years I can pretty much predict what next months bill will be. Even with the converter and inverter losses it's still way cheap power. And I have the peace of mind that everything electrical on the property is UPS'ed.

I've rambled off topic long enough.



I can completely understand this from a be self sufficient / increasing tarrif prices / silly regulations point of view but.... Have you ever done the maths on the total outlay and running / maintenance cost compared to just buying power from the electricity company?


Rich

"... total outlay and running / maintenance cost compared to just buying power from the electricity company?"

Yes, since 1998. I re-evaluate every 6 months or so.

Initially in 1999 the power company gave me an estimate of $20,000+ to run in power to my place (I'm almost a 1/4 mile off the main road and I'm the only customer on my road, which I own). As a submariner (nuc powered) I had been investigating being self sufficient since the late 70's. So needless to say instead of giving them 20 grand I spent it on RE hardware (batteries, solar, wind, genny's, etc.). In Decmber of 2005 I "bit the bullet" and had them connect me to the grid (at a cost of ~$5,000). At the time regular service was $0.055/KWh and off peak was $0.028. I still generated most of the power and bought small amounts from them during peak demands (water heater, electric stove). Then 3 years ago got into BTC mining and became a heavy power purchaser (~$2,500/Month). Recently my power coop announced rate hikes as a result of the EPA's "carbon tax" (CPP Clean Power Plan). This initiated, and is still ongoing, a research endeavor regarding the future pricing and availability of electrical power. Basically my research and analysis to date indicates that within the next 5-10 years electricity will become a luxury item, nationwide. Priced out of the reach for low and middle income wage earners. My renewed self generation fervor revolves around "getting in front of" an impending decrease in quality of life. Survival.

A properly designed renewable generation system, OVER TIME, will always be cheaper (and OBTW better for the environment) than buying power from an external source. For one simple reason, You're buying power with today's dollars and "locking in" your cost / KWh over the life of the system (15-30 years). As such I am NOT a fan of tax incentives, rebates, or other incentives. Those can disappear and have disappeared with the stroke of a pen and public opinion. An improperly designed system will never break even/pay for it's self. It's real easy to design a system wrong and are typically the systems that fossil fuel generation company's like to broadcast about.

I'm a fan of a particular kind of nuclear power not currently operating here in the US. Thorium fuel cycle molten salt reactors. Having lived for 12 years less than 250 feet away from the core of a LWP (light water pressure) reactor (Nuclear powered submarine) my previous statement comes from experience. LWP's are a problem looking for a place/time to happen. Checkout: http://www.ted.com/talks/kirk_sorensen_thorium_an_alternative_nuclear_fuel

207  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 12, 2016, 07:46:36 AM
This just in, Bitfury has tied the release date and sales of their 16nm miners to when Valve releases Half-Life 3, we should see them "any day now"!

 Roll Eyes


As to the solar discussion, when I move here shortly I am going to look into a solar setup, but what it will not be is grid-tied.  I don't like the power company telling me what I can and can't do and I'm not going to help their cause by selling them my power that I generated.  I'm going to use it all, it's mine mine mine!


I could not agree more.

Without a grid-tie, you need a huge batterybank.
Or are you only going to mine during sun hours? Or are you going to manually connect the miners to the grid when the sun goes down? Tongue
Batteries are expensive!

So is paying endlessly increasing (due to rate increases) electrical bills.

Where I am, my electrical coop(s) are real crooks. They managed to get into law a requirement for the owner to have a liability insurance policy. The cost of the policy exceeds even the maximum revenue stream for selling power back (+ net excess generation metering) as an IPP (Independent Power Producer 40 KW nameplate capacity or less) under the Minnesota Statute. If you exceed 40Kw nameplate capacity generation you're classified just as they are and have to negotiate a contract, typically at the "avoided cost rate". Which is the lowest priced rate class, and here, about $0.005 per Kwh (That's 1/2 cent per Kwh). They sell regular service power to the retail customer @ $0.1235. Hence my crook comment.

I decided long ago (1999) that it would be a cold day in Hell and the little devils would go skating when they got 1 miliwatt from me. F'em if they can't take a joke.

Oh, and yes, I have a sizable battery bank of U.S, Battery L16HC XC2's (20 Hour Rate: 420) and ~150 lbs each. The first batch of these wore out after 10 years of service, I abused them, else I'd a got 15 years out them. http://usbattery.com/products/6-volt-batteries/us-l16hc-xc2/ Best "bang-for-the-buck".

To avoid the insurance cost, I run a "hybrid" system. Solar charges the batteries (and a little AirX, which is really just a toy comparatively). If the solar charging system comes up short for the day, I have a Morningstar relay driver that senses battery voltage and turns on some high current (100A each) RV power converters (battery chargers http://www.amazon.com/gp/product/B00F8MC45E?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00) feed by off peak power ($0.048 per Kwh) at night. At 8:30 AM it turns them off in preparation for another solar charging day. This is by far cheaper than running a gas/diesel fueled generator (and a hell of a lot quieter) for "make up" power/charging. The size of the bill at the end of each month is indicative of how "sun shiny" the month was. After 17 years I can pretty much predict what next months bill will be. Even with the converter and inverter losses it's still way cheap power. And I have the peace of mind that everything electrical on the property is UPS'ed.

I've rambled off topic long enough.

208  Bitcoin / Hardware / Re: Community Miner Design Discussion on: March 09, 2016, 03:31:22 AM
I was in a rush and thought that was a blade fuse! Maybe this one? Their list of current excess (pardon the pun) is here

this one is 2 usd  it is on your list


http://www.allelectronics.com/make-a-store/item/fhp-31/weatherproof-atc-blade-fuse-holder-10-ga-wire/1.html


with a 10 gauge wire and a protective cover it is a great item.  but it is 2 usd

we have a link for bare bones 1000 for 84 bucks  you need two so 17 cents.  I can tell you your item is less work and pretty good quality,

  but 2 usd vs 17 cents  I think   the 17 cents deal would be picked.

now if you found that 2 dollar item for 50 cents  it would be good since it is less work the the 17 cent deal.

and sidehack may still prefer the 17 cent deal .  I have not done as much of this work as he has. he knows a bit more then me.



In my electronic tinkerings I've bought stuff from All Electronics.
Really good pricing because they buy overstocks, discontinued items, and production overruns.
As such, a manufacturer of boards might have a concern that spec'ed parts from them may not always be available or available at the current cost.
Beyond price I'd be thinking about the supply chain and all that brings to the table.

Just sayin'
209  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 08, 2016, 06:18:24 AM
After I got out the Navy (Sub sailor) spent many a year in Dover DE. Am familiar with the trickery in government in that region.

Here we don't have a choice for power suppliers. It's a coop run by corrupt administrators. We're currently paying $0.13/KWh. Who signed a 38 year (terminating in 2045) sole source purchase agreement with a company that only has coal fired generation. Whether one agrees with it or not, coal is doomed. The EPA just won a case in the supreme court over the CPP (Clean Power Plan) which is the beginning of a carbon tax. When that is implemented (again whether or not one supports such a concept) it will drive coal fired electrical costs through the roof. While no one can precisely predict future pricing 5, 10, or 20 years out, my estimates indicate that within the next 10 years it will double or triple. This will put electrical consumption into the luxury item category.

I too am disabled and, personally, live on a fixed income (like other seniors). Fortunately I had the foresight and wherewithal to own my home (i.e. no mortgage). Many, if not all of my peers don't. Many of those that are surviving exclusively on SSA are currently making choices between food and drugs. If their electrical costs doubled or tripled I fear we will be finding them frozen in the dark, literally. All due to a handful of the greedy few.

I have tried to work within the system to reform it to no avail. The only option left is for me is to attempt to insulate myself from the pending doom and if able assist the few I can.

From a personal electrical consumption basis, I'm well on my way to being electrically independent. Have a plan in place where by the time the "snow flies" this year I will attain that goal. BTC has played an important role. And while I'm in the giving credit where credit is due mode sidehack and novak have been instrumental in many respects.

Somewhere near the end of this month I'm going to "trip the mains" on the domicile isolating me from the grid. At the same time I'll shut off all the .8 and .5 W/GH/s miners in anticipation of sidehack's BF replacement boards.As I have a BUTTLOAD of S1/S3/C1/S5's looking for an up grade's I'll never shut off the compac's and the U2's as they are just too cute  Grin

The previous rant was WAY off topic, so I'll refrain going forward.
210  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 08, 2016, 03:02:00 AM
This just in, Bitfury has tied the release date and sales of their 16nm miners to when Valve releases Half-Life 3, we should see them "any day now"!

 Roll Eyes


As to the solar discussion, when I move here shortly I am going to look into a solar setup, but what it will not be is grid-tied.  I don't like the power company telling me what I can and can't do and I'm not going to help their cause by selling them my power that I generated.  I'm going to use it all, it's mine mine mine!


lol to bad i don't play those type games I  play stuff like wow Swtor mmo's  more . really the power company has more control, sigh .  i may have to keep it for my self to, any way waiting for a installer to come and give me price and explain it, i have few questions, we can get it were i live but not on the roof, i like that idea better . no messing up our new roof .

I pay $0.58 - $0.68 per watt for the panels. UL listed. 60 cell 250W
Last 2.25 KW was @ $0.74 per watt
Where I live, northern MN, panels on the roof is suicide.
Mine are on racks on the ground. Can't fall off the ground.

Check your states net metering laws regarding the price (rate) they buy back, usually it's one sided.
And the increase in your home owners policy.

Net - net it may not be worth it or a potential loss.
I've been doing wind and solar for 10+ years, learned alot along the way.
Am willing to share.

Am finishing up a report/analysis on the state of our electrical system here in the US.
The future does not bode well.

admin@planetcrypto.com

211  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 08, 2016, 12:10:25 AM
Have off grid solar running most of the domicile.
The 100A @ 12V nominal battery chargers (RV industry calls'em converters) use 3 40A ATC fuses, I assume their wired in parallel.

Shout out to toptek. Thought I was the only hexa-genarian in the crowd.  Grin
212  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 07, 2016, 11:46:00 PM
Well, mining is self-regulating. The halving is going to hurt a lot, but it's not like bitcoin's going to disappear. What becomes unprofitable to run will no longer be run, coin prices will go up, fees will go up, and the system will keep on running. If anything has a chance to be profitable, it'll be the most efficient chip available at the time. That's dependent a lot on initial cost, but the market is adjustable as well - if BitFury can't sell enough of them at whatever price, they'll either use 'em themselves or lower the price. There are way too many variables to make any sort of accurate prediction, but the fact that pretty soon 99% of the world won't be able to turn a buck with 0.3J/GH gear helps the assumed viability of 0.1J/GH gear.

+1

"You can ignore reality, but you can't ignore the consequences of ignoring reality." -- Ayn Rand

or

"If 50,000 people share a bad idea, it's still a bad idea." -- J. Schlenker
213  Bitcoin / Hardware / Re: Community Miner Design Discussion on: March 07, 2016, 11:38:32 PM

Nice put in a 25 amp blade and safety all around.

Yeah I know the tweakers will want to put in a 30 amp blade but still make spec with that socket.

That is also a troubleshooting technique called "smoke testing".
Put in too large of a fuse and see what smokes.
Then replace it.

If the larger fuse still blows, replace with larger fuse and repeat.

 Grin Grin Grin Grin
214  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 06, 2016, 10:22:42 PM
Like I said, unable to relate to most people these days.

But discussion like that belongs in a different place.

I can relate to not relating (said in a serious tone and not intended as a play on words).
And I've always been in a different place physically and mentally (said in a self deprecating serious tone).
215  Bitcoin / Hardware / Re: Community Miner Design Discussion on: March 06, 2016, 10:11:47 PM
sidehack

I have a design requset:
Allow the hash board input voltage to be from 10.5Vdc to 15.5 Vdc.

Here's the reason:
An input V range of 10.5V-15.5V would allow the boards to be driven by a battery bank which is in turn charged by solar.
And eliminates the need for a high current sepic converter

Here's a sample scenario that would scale:
3x 60 cell panels (250W-300W) in series (nominal 105Vdc input) feed to a Morningstar MPPT-60 (other brands exhibit similar tolerances) that charges the battery bank.
In this scenario, one can expect or should design for, a battery bank voltage to swing from 10.5V (completely discharged) to 15.5V (fully charged in winter and/or battery equalization charge levels).

Driving a miner directly from a DC source (12V battery bank) has at least one advantage, it escapes the losses in converting DC to AC (i.e. inverter inefficiencies).
Inverter efficiencies can be as low as 82% (sometimes worse with cheap China originated inverters).


Another request, regardless of input source, is that the hash boards implement a low voltage cutoff @ 10.5V.
This would prevent an over current condition when the bucks are feed a low supply voltage.
Which would assist in saving the hash board when a PSU screws up or is overloaded.

Maybe a simple fuse inbetween the PCI power input and the buck(s) supply rail???

Thanks in advance for the consideration.

Pup Tentacle
216  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 06, 2016, 10:09:21 PM
Things specific for my design should be addressed in the Community Miner Discussion thread, rather than a general Bitfury thread.

Roger that.

Also, I don't drink coffee.

To each his own. Grin

I need 2 cups in the AM or waking up takes too long.
217  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 06, 2016, 04:44:25 PM
Odd you mentioned the Prisma fires as our last Prisma burst in flames about 2 weeks ago.
Quite an impressive little foul smelling "campfire".
It continued to hash, for a short time, during the fire.
I let run, until it self destructed.
As it was obvious the Prisma was toast, and was curious to see just how long it would hash before giving up the ghost.

The IBM PSU (with your most durable adapter board) just hunkered down and keep feeding it current.
Both the supply and adapter board survived the ordeal. Grin
The Prisma not so much. Huh
218  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 06, 2016, 04:23:15 PM
Morning sidehack, hope you've had your morning coffee. I'm working on #2.

I have a design requset:
Allow the hash board input voltage to be from 10.5Vdc to 15.5 Vdc.

Here's the reason:
An input V range of 10.5V-15.5V would allow the boards to be driven by a battery bank which is in turn charged by solar.
And eliminates the need for a high current sepic converter

Here's a sample scenario that would scale:
3x 60 cell panels (250W-300W) in series (nominal 105Vdc input) feed to a Morningstar MPPT-60 (other brands exhibit similar tolerances) that charges the battery bank.
In this scenario, one can expect or should design for, a battery bank voltage to swing from 10.5V (completely discharged) to 15.5V (fully charged in winter and/or battery equalization charge levels).

Driving a miner directly from a DC source (12V battery bank) has at least one advantage, it escapes the losses in converting DC to AC (i.e. inverter inefficiencies).
Inverter efficiencies can be as low as 82% (sometimes worse with cheap China originated inverters).


Another request, regardless of input source, is that the hash boards implement a low voltage cutoff @ 10.5V.
This would prevent an over current condition when the bucks are feed a low supply voltage.
Which would assist in saving the hash board when a PSU screws up or is overloaded.

Maybe a simple fuse inbetween the PCI power input and the buck(s) supply rail???

Thanks in advance for the consideration.
219  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 06, 2016, 03:41:15 PM

The buck to drive it is another potential bone of contention. Cuz' it's drawing just under 40A (38.8A) @ a Vcore of ~.580V PER CHIP. Imagine the current draw of a string of 3 or 4 chips.

 Current would be the SAME for a "string" of any number of chips (not counting I2R losses in the power distribution traces and such) - just have to run the voltage higher.
 So a buck for 4 chips in a string would still be just under 40A but would be supplying about 2.32 volts

Guess I'm "cornfused" Tongue
And your post is a learning/educational experience and a Homer Simpson moment for me. Doh!
I was thinking that the strings of chips would be, for lack of better words, wired up in parallel (regarding Vcore) versus in series.
Strings in series makes a buttload more sense from a simplicity standpoint (if nothing else component count) but loses the redundancy (or fault tolerance) of chips in parallel.

I come from a military background where things are grossly over engineered AND where cost is no object, so I think and engineer things in terms of continued operation with reduced capabilities.
i.e. everything is mission critical.
Obviously BTC mining doesn't exhibit that criteria.
It also explains why I have a box full of dead BM hash boards.

Thanks for the brain working.
220  Bitcoin / Hardware / Re: Bitfury: "16nm... sales to public start shortly" on: March 05, 2016, 10:51:23 PM
Just a little niggle on
"Non boiling fluid provides little convection fluid flow, thereby leaving hot fluid on/near the surface of the chip. And even then, the fluid didn't boil."

In a fairly open system yes.

In the vids BF shows it's a safe bet that the tank of Novec is near ambient temp hence the lack of phase-change seen. Still pretty impressive as ja that shows that the power the chip is dissipating remains rather low.

In a densely packed system with 1-2 cm between the boards like BF's data tanks have thermal siphon effects kick in that will created a surprising amount of flow over the boards & chips. With Novec's very low viscosity that should translate into a pretty decent amount of flow circulating over the boards and back down the sides of the tanks. Once the whole tank of fluid gets near the boiling point then it should get quite lively in the tanks.

That is provided the non-insulated data tanks don't already have enough outside surface area to keep the Novec below its boiling point. Doubt that is the case. If it is they'll just pack in more chips Tongue

Concur 99.9%.
I was referencing some of our early tests with Novec 7100 and the S3 boards (vid here: https://www.youtube.com/watch?v=gcb9TyQP5ZA ) regarding what it takes to boil 7100. Ambient during the our vid is 70F-80F. and is probably similar to Ambient in the BF vids. In operation, the tank was definitely warm to the touch. Board separation clearance was ~2mm (.006 inches) (i.e. chip surface to spacer plate distance). We fabricated spacer plates out of polycarbonate to minimize the amount of Novec required in the tank. Tank ran at 1 bar (1 atmosphere, 0 relative pressure), so not a pressurized system. Minimizing the amount of fluid contacting the chip/board promoted convection flow (along with the "sparkiling bubbles"). We experimented with clearances down to 1mm, and it worked. Just wasn't comfortable with that little clearance. Am familiar with Alex's Data Tank design. Didn't know there was that much clearance, never thought to look. We also played around with and developed blending tables for the various Novec fluids in an attempt to "dial in" the boiling point for a particular application.

"... is near ambient temp hence the lack of phase-change seen." Raising Ambient would expedite boiling and the converse is also true. Most of the heat removal, in 2-phase, is due to phase change and not in the warming of the fluid to the boiling point (unless of course there is a HUGE delta T between fluid temp and boiling point, but that effect will be short lived as the fluid comes up to temp). The fact that the fluid in the BF vid isn't boiling tends to indicate the chip surface hasn't reached the boiling point of the fluid, whatever it was, and am assuming it was a Novec fluid. Cuz' the Data Tank used by BF, at least initially, exclusively used the 3M product. The fluid in the BF vid, were I to hazard a guess, would be one of 7100's bigger brothers: 7300, 7400, or 7600. This is the difference between immersion cooling, say using an oil which never undergoes a phase change and 2 phase immersion cooling using an engineered/calibrated boiling point fluid which does. Heat removal and consequently power density are dramatically better when comparing immersion versus 2-phase immersion owing to Novec's latent heat of vaporization curve.

Concur
"That is provided the non-insulated data tanks don't already have enough outside surface area to keep the Novec below its boiling point. Doubt that is the case." Aluminum tanks dissipate/leak more heat into the surrounding space than, say, polycarbonate. Or better yet, an insulated polycarbonate container/tank. This is not desirable in 2-phase. As part of the design is to convey the heat away to a heat management system and not into the local area.

Sorry about the rant, I'll shutup now.
Pages: « 1 2 3 4 5 6 7 8 9 10 [11] 12 13 14 15 16 17 18 19 20 21 22 23 24 »
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines Valid XHTML 1.0! Valid CSS!