[VIDEO] Butterfly Labs (BFL) Bitforce SC ASIC Test

[Entropy-uc]

I managed to track down the chart I was talking about above.

My calculations put their reported power density right in the middle of the Pentium 4 space.

BFL is going to have to completely re-engineer their thermal solution if they can't get the power reduced by at least 30%.

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[SebastianJu]

I managed to track down the chart I was talking about above.

My calculations put their reported power density right in the middle of the Pentium 4 space.

BFL is going to have to completely re-engineer their thermal solution if they can't get the power reduced by at least 30%.

Im not sure but isnt the graph misleading? I mean you only use the chip for w/cm² but one should take the fuel rod of a nuclear reactor only then too, isnt it? And then this value cant be true anymore am i wrong? It doesnt look correct to me that the power density in a chip can be near the power density created by a nuclear reaction. But im no physicist.

[ShadesOfMarble]

"It doesnt look correct to me" -> logarithmic scale

[SebastianJu]

"It doesnt look correct to me" -> logarithmic scale

Yes, but even then... the scale shows something like 90 W/cm² for a pentium 4 and maybe 250 W/cm² for a nuclear reactor? Thats the whole building then isnt it?

[Ekaros]

"It doesnt look correct to me" -> logarithmic scale

Yes, but even then... the scale shows something like 90 W/cm² for a pentium 4 and maybe 250 W/cm² for a nuclear reactor? Thats the whole building then isnt it?

90W under load seems to be true.

There is reason why nuclear rods are submerged in water, other than radiation. You really have to consider size difference. Pentium 4 chips were around 2cm^2 where as nuclear rods are much larger.

[jedunnigan]

Entropy can you be a bit more specific? What exactly would happen? Before a fire, that is...

[johnyj]

I guess in this case, even the VRM need to be actively cooled

[tvbcof]

...
Im not sure but isnt the graph misleading? I mean you only use the chip for w/cm² but one should take the fuel rod of a nuclear reactor only then too, isnt it? And then this value cant be true anymore am i wrong? It doesnt look correct to me that the power density in a chip can be near the power density created by a nuclear reaction. But im no physicist.

Seems intuitively OK to me.  The reaction in a nuclear reactor is a controlled criticality and needs to be within a manageable density range for long duration use.  It is also large in size so the total power output is quite large.  A rocket engine only runs briefly and consumes a huge amount of high energy fuel per unit time.

It would be interesting to know the power density within a fusion device in the brief moment the pit goes critical.

[superfastkyle]

So what you really mean is primeAsic now has the same amount of proof that Avalon does, lol

The primeAsic scammers just released a video that shows just as much proof IMO

[Entropy-uc]

Entropy can you be a bit more specific? What exactly would happen? Before a fire, that is...

The first thing is a huge heat sink and a really loud fan.  That's what we had on p4.

If your processor runs too hot, you get diffusion in the various materials that make up the device - this dramatically reduces the working life of the processor due to a range of failure modes.  Ask the GPU mining guys how fast that can happen.   

In the shorter term resistances rise with temperature, driving power demand up in a negative feedback loop.  I would guess that test video was just about the amount of time they could run chips without having the magic smoke come out of some components.

I don't know what I would do in BFL's shoes.  There isn't enough data to really understand what the situation is.  But what they reported is not good in the short term.

[SLok]

Code:

bfgminer version 2.99.2 - Started: [2013-03-30 23:37:17] - [  0 days 00:01:57
------------------------------------------------------------------------------
 5s:17.85 avg:16.58 u:14.26 Gh/s | A:342 R:0 S:0 HW:0 U:179.6/m
 ST: 2  DW: 10  GW: 3  LW: 494  GF: 0  NB: 1  AS: 0  RF: 0  E: 2.08
 Connected to 192.168.1.1 diff 8 with stratum as user test
 Block: ...ee2e8a72 #3123  Diff:153  Started: [23:37:17]  Best share: 528
------------------------------------------------------------------------------
 [P]ool management [S]ettings [D]isplay options [Q]uit
 BFL 0:  45.0C         | 17.83/17.52/14.58Gh/s | A:343 R:0 HW:0 U:180.16/m
------------------------------------------------------------------------------

 [2013-03-30 23:38:52] Stratum from pool 0 requested work update
 [2013-03-30 23:38:52] Accepted 0ecf365f BFL 0  Diff 17/1
 [2013-03-30 23:38:53] Accepted a91d942c BFL 0  Diff 1/1
 [2013-03-30 23:38:53] Accepted 15d55ee2 BFL 0  Diff 11/1
 [2013-03-30 23:38:53] Accepted be2972c6 BFL 0  Diff 1/1
 [2013-03-30 23:38:53] Accepted 9e87d2fd BFL 0  Diff 1/1
 [2013-03-30 23:38:53] Accepted 7f854200 BFL 0  Diff 2/1
 [2013-03-30 23:38:54] Accepted 03c5d641 BFL 0  Diff 67/8
 [2013-03-30 23:39:08] Accepted 040aab96 BFL 0  Diff 63/8
 [2013-03-30 23:39:09] Accepted 14997fe3 BFL 0  Diff 12/8
 [2013-03-30 23:39:10] Accepted 123ded4b BFL 0  Diff 14/8
 [2013-03-30 23:39:11] Accepted 0453e37f BFL 0  Diff 59/8
 [2013-03-30 23:39:14] Accepted 06bd2321 BFL 0  Diff 37/8

https://bitcointalk.org/index.php?topic=78192.msg1707177#msg1707177

[k9quaint]

Entropy can you be a bit more specific? What exactly would happen? Before a fire, that is...

The first thing is a huge heat sink and a really loud fan.  That's what we had on p4.

If your processor runs too hot, you get diffusion in the various materials that make up the device - this dramatically reduces the working life of the processor due to a range of failure modes.  Ask the GPU mining guys how fast that can happen.   

In the shorter term resistances rise with temperature, driving power demand up in a negative feedback loop.  I would guess that test video was just about the amount of time they could run chips without having the magic smoke come out of some components.

I don't know what I would do in BFL's shoes.  There isn't enough data to really understand what the situation is.  But what they reported is not good in the short term.

Isn't the usual response to too much heat to lower the clock speed and/or lower the voltage?
The unusual response being custom machined copper water blocks with liquid cooling.

[atomicdog]

after watching the video i don't know how they could give an estimate of shipping in a week given what the video shows.  there are a myriad of questions that the video brings up.  i don't see how the solution could only be adding additional voltage regulators to a new pcb.  do they even know if they will need a larger heatsink/fan and will it even fit in their nifty case? wow what a butterfluck...

[tvbcof]

...
It would be interesting to know the power density within a fusion device in the brief moment the pit goes critical.

that would be such a big number it's hard to think about.  And so classified I'm a little nervous even replying to you.

Were only talking order-of-magnitude estimates, and the megaton yield and rough dimensions of are reasonably well know.  But not by me, however, and I don't feel like looking it up or embarrassing myself with the mathematics which are rusty.  Suffice it to say, though, that 'big' is probably descriptive enough

[antirack]

Bottom line:  Intel P4 processors were the highest power density systems we shipped.  Once you get in that range, really bad things happen.

I believe IBMs Power PC 4 CPU had some hot spots of up to 140 W/cm2. Apple's G5 had two dies under the hood with a total flux of around 200 W/cm2. I think your "really bad things happen" is spot on, Apple had a leaking water cooling system

[beekeeper]

40W per square centimeter is way too much. Put your palm around a light bulb. Then imagine all that heat burning your hand comes trough a finger nail, which would be the chip..

As someone said:

The more important question is:
WILL IT BLEND?

or, "will it melt?"

Ofc, it is possible to design packages and cooling systems to use this chip, but I doubt it can be done safely in a week.

[PulsedMedia]

guys guys, the chip power usage is not the full 195W, it's the whole board.
The board itself will consume a lot of the power, most in this case due to going badly out of spec.

If the power reqs go far beyond their nominal range efficiency goes shit, requiring higher amperage for the specific output.
Power regs ran beyond their spec can consume insane amounts of power, which mostly goes in to heating.
So if it was rated for 5A (60W), but the board required 7.5A (90W), due to efficiency going shit it would jump straight to 9A, and further due to heat above 10A. Then the traces might not be large enough for the reg, further putting demand for higher current due to increased resistance. Voltage also drops, it might reach a point where voltage drops, and again demand for current goes higher. To get 20A @ 3.3V with 11V takes a lot more current than at 12V. At 11V it's 6A, at 12V it's 5.5A.
Current is what causes things to heat up and is most affected by resistance. You can probably transmit 1kW @ 1000V over the same traces which can barely handle 50W @ 3.3V. (Given insulation is sufficient)

All those figures are just speculative, depends on the regs used, trace sizes etc. Just basics really, but you get the idea.

So it's entirely possible adding another reg there will fix it.

I'm not an electronics engineer, but i've made my dabble into electronics

[wndrbr3d]

guys guys, the chip power usage is not the full 195W, it's the whole board.
The board itself will consume a lot of the power, most in this case due to going badly out of spec.

I'm no physics major, but my pappy told me long ago that heat is the result of wasted energy. So I don't think it matters WHERE the energy is being spent, odds are it'll generate a fair amount of heat.

[Meizirkki]

guys guys, the chip power usage is not the full 195W, it's the whole board.
The board itself will consume a lot of the power, most in this case due to going badly out of spec.

There's no way they designed the board for 60W total. Regulators aren't going to do twice their designed output.

[Frizz23]