6 ms·

If y'all missed it, the Cerebras CS-2 teardown is amazing: https://www.youtube.com/watch?v=pzyZpauU3Ig https://www.youtube.com/watch?v=pzyZpauU3Ig The enginee

If y'all missed it, the Cerebras CS-2 teardown is amazing: https://www.youtube.com/watch?v=pzyZpauU3Ig https://www.youtube.com/watch?v=pzyZpauU3Ig The engineering to handle that power density is insane. Technically its less power per mm^2, but the chip is the size of a dinner plate. EDIT: The video was taken down, but looks like the web archive got it: https://web.archive.org/web/20230812020202/https://www.youtube.com/watch?v=pzyZpauU3Ig https://web.archive.org/web/20230812020202/https://www.youtu... As well as Vimeo (thanks morcheeba): https://vimeo.com/853557623 https://vimeo.com/853557623

webstrand 3y ago
That video is no longer available?
- brucethemoose2 3y ago
  Huh. I copied the link from here: https://news.ycombinator.com/item?id=37096214 https://news.ycombinator.com/item?id=37096214 There are reposts with that same link. Maybe it revealed too much and was taken down?
morcheeba 3y ago
Is it the same as this video? https://vimeo.com/853557623 https://vimeo.com/853557623
- brucethemoose2 3y ago
  Yeah, that's it!
rwmj 3y ago
That video and the cooling system is insane. Insanely cool even. Thanks for posting. I wonder, how do all the contacts in the 20,000A power distribution plate that is bolted on top of the wafer-scale die line up? The engineering involved in just making that part work must be crazy.
- vpribish 3y ago
  20,000 Amps has to be a mis-statement. or there's some qualifier they are not mentioning. it doesn't look like an industrial arc-furnace
  - rwmj 3y ago
    She definitely says "the way we bring 20,000 amps into the front side of the wafer" (around 2'17'' into the video). It does seem an awful lot.
    - FastFT 3y ago
      Core voltage is going to be in the ballpark of 1V, and given the stated power consumption is 15kw that means a minimum of 15kA. So, it is indeed a lot but the math checks out.
      - vpribish 3y ago
        how much of that power actually reaches the chip though? (it's hilarious that this is one chip)? this thing is mostly a water pump - I just can't - everything about it is just wild
        Kirby64 3y ago
        Most of it. The water pump and other stuff consumes probably less than 500W total. There's some efficiency loss in the actual power converters, but they're likely designed to be >95% efficient (probably >98%), otherwise cooling them would be a nightmare.
      - bgnn 3y ago
        7nm core voltage is 0.75V. If they want good reliability, 0.7V underdrive is understandable. So, 2.2kA at 0.7V sounds reasonable to me.
    - pwg 3y ago
      This pdf (https://f.hubspotusercontent30.net/hubfs/8968533/CS-2%20Data%20Sheet.pdf https://f.hubspotusercontent30.net/hubfs/8968533/CS-2%20Data...) says the power supplies are 6+6 redundant 4kW supplies. Assuming 100% utilization (not realistic, but it makes the "math" easy) that's 24kW of "power supply". If we presume the wafer consumes a large percentage of that (say 20kW out of the 24kW max) and that they are feeding the "wafer" with DC at 1v, then they /do/ need to feed in 20,000 amps to deliver 20kW of power at 1v. So yes, 20kamp is a lot of current, but it is within the "power budget" the device seems to express in its marketing material.
murphyslaw 3y ago
Christ, 850000 cores!
- MuffinFlavored 3y ago
  I wonder if it can do well at crypto mining... :D
throwawaymaths 3y ago
I hear even A100s have a not very good shelf life and need to be replaced relatively frequently. Wonder how it is for cerebras
samstave 3y ago
Jiminy Crickets - that Cerebras is dope - dont miss the only other tech vid from Rebbecca: https://vimeo.com/lewie221 https://vimeo.com/lewie221 <-- About CFD. Weirdly - CFD has been zeitgeisting me here on HN the last couple of days - I have been talking about FluidX3D - and have been attempting to compile it this AM locally on windows with failures (about to see if I can plop it into a docker) Never thought youd be doing CFD calc to keep a stable temp flow over 1.6 trillion transistors to keep them evenly cooled - did ya? -- In watching that above CFD vid - I was led to start thinking if CFD could be applied to the ways AI models/GPTs communicate or calculate. I wonder if one could use an CFD anaolgies to the data flows through AI models/systems such as OpenAI. It would be interesting to look at the OpenAI GPT Store's entanglements through the lens of CFD and determine where relations might be made for how stacking GPTs might communicate through their Tapestry. An CFD-heads care to dive in? I wonder if one were to treat 'token flow' in a CFD manner in which one can visualize how tokens are assigned attention scores. GPT claims to not be able to visualize the attention score matrix for the tokens - but assuming it could - it would seem as though it should be easy to visualize attention matrices in a CFD visual. https://i.imgur.com/jzZ1wsP.png https://i.imgur.com/jzZ1wsP.png -- Or I sound like an idiot. Lets ask GPT. haha --- (also - in super expensive machines , why aren't sheets of AeroGels used as gaskets if you want thermal separation. Imagine taking an AeroGel powder and mixing it with Silicone - and having a super thin, flexible material, such as D3 - which has a melting point of 134c/273f.... So - mixing aerogel with D3 as a gasket would be good, and with D3 being a non-newtonian it works well for shocks. A space gasket as it were.
robomartin 3y ago
I can appreciate the thermal engineering that has gone into this. I have executed some extremely challenging thermal designs over time. They generally used heat transfer plates of the type shown in this video. My largest design as approximately 23 x 12 inches. Maintaining thermal efficiency and uniformity across the entire surface is where the real challenge lies. We had an extremely tight uniformity specification (0.1 deg C). This could only be achieved through a complex design process that entailed writing genetic algorithms to evolve and test solutions using FEA. In the end it was a combination of sophisticated impingement cooling and other techniques that did the job. That project was seriously challenging. I like projects that absolutely kick my butt. This one definitely did.
- allenrb 3y ago
  Can you share anything more about the project? This sounds fascinating.
  - robomartin 3y ago
    Sadly, I can't share details or the application domain. I can tell you that we worked very hard to try and see if we could accomplish the objectives using forced air (fans). That effort involved laser-welded fins with sophisticated airflow management, techniques to break-up the boundary layer (which impedes optimal heat transfer) and powerful centrifugal fans. It worked well, yet it was large and sounded like a jet engine. Ultimately, while still complex, fluid-based thermal management offered a far more compact solution that could exist in a room with people not having to wear hearing protection. In addition to that, with a fluid-based system you can move the hot side to a different room.
    - KMag 3y ago
      Very interesting, though a bit odd to contrast air cooling with fluid cooling, given it takes pretty extreme conditions for air to not be a fluid.
      - 3y ago
tomcam 3y ago
That's wild. Especially the rough similarity to an air-cooled 3 cylinder engine.

webstrand 3y ago

That video is no longer available?

brucethemoose2 3y ago
Huh. I copied the link from here: https://news.ycombinator.com/item?id=37096214 https://news.ycombinator.com/item?id=37096214 There are reposts with that same link. Maybe it revealed too much and was taken down?

morcheeba 3y ago

Is it the same as this video? https://vimeo.com/853557623 https://vimeo.com/853557623

brucethemoose2 3y ago
Yeah, that's it!

rwmj 3y ago

That video and the cooling system is insane. Insanely cool even. Thanks for posting. I wonder, how do all the contacts in the 20,000A power distribution plate that is bolted on top of the wafer-scale die line up? The engineering involved in just making that part work must be crazy.

vpribish 3y ago
20,000 Amps has to be a mis-statement. or there's some qualifier they are not mentioning. it doesn't look like an industrial arc-furnace
- rwmj 3y ago
  She definitely says "the way we bring 20,000 amps into the front side of the wafer" (around 2'17'' into the video). It does seem an awful lot.
  - FastFT 3y ago
    Core voltage is going to be in the ballpark of 1V, and given the stated power consumption is 15kw that means a minimum of 15kA. So, it is indeed a lot but the math checks out.
    - vpribish 3y ago
      how much of that power actually reaches the chip though? (it's hilarious that this is one chip)? this thing is mostly a water pump - I just can't - everything about it is just wild
      - Kirby64 3y ago
        Most of it. The water pump and other stuff consumes probably less than 500W total. There's some efficiency loss in the actual power converters, but they're likely designed to be >95% efficient (probably >98%), otherwise cooling them would be a nightmare.
    - bgnn 3y ago
      7nm core voltage is 0.75V. If they want good reliability, 0.7V underdrive is understandable. So, 2.2kA at 0.7V sounds reasonable to me.
  - pwg 3y ago
    This pdf (https://f.hubspotusercontent30.net/hubfs/8968533/CS-2%20Data%20Sheet.pdf https://f.hubspotusercontent30.net/hubfs/8968533/CS-2%20Data...) says the power supplies are 6+6 redundant 4kW supplies. Assuming 100% utilization (not realistic, but it makes the "math" easy) that's 24kW of "power supply". If we presume the wafer consumes a large percentage of that (say 20kW out of the 24kW max) and that they are feeding the "wafer" with DC at 1v, then they /do/ need to feed in 20,000 amps to deliver 20kW of power at 1v. So yes, 20kamp is a lot of current, but it is within the "power budget" the device seems to express in its marketing material.

murphyslaw 3y ago

Christ, 850000 cores!

MuffinFlavored 3y ago
I wonder if it can do well at crypto mining... :D

throwawaymaths 3y ago

I hear even A100s have a not very good shelf life and need to be replaced relatively frequently. Wonder how it is for cerebras

samstave 3y ago

Jiminy Crickets - that Cerebras is dope - dont miss the only other tech vid from Rebbecca: https://vimeo.com/lewie221 https://vimeo.com/lewie221 <-- About CFD. Weirdly - CFD has been zeitgeisting me here on HN the last couple of days - I have been talking about FluidX3D - and have been attempting to compile it this AM locally on windows with failures (about to see if I can plop it into a docker) Never thought youd be doing CFD calc to keep a stable temp flow over 1.6 trillion transistors to keep them evenly cooled - did ya? -- In watching that above CFD vid - I was led to start thinking if CFD could be applied to the ways AI models/GPTs communicate or calculate. I wonder if one could use an CFD anaolgies to the data flows through AI models/systems such as OpenAI. It would be interesting to look at the OpenAI GPT Store's entanglements through the lens of CFD and determine where relations might be made for how stacking GPTs might communicate through their Tapestry. An CFD-heads care to dive in? I wonder if one were to treat 'token flow' in a CFD manner in which one can visualize how tokens are assigned attention scores. GPT claims to not be able to visualize the attention score matrix for the tokens - but assuming it could - it would seem as though it should be easy to visualize attention matrices in a CFD visual. https://i.imgur.com/jzZ1wsP.png https://i.imgur.com/jzZ1wsP.png -- Or I sound like an idiot. Lets ask GPT. haha --- (also - in super expensive machines , why aren't sheets of AeroGels used as gaskets if you want thermal separation. Imagine taking an AeroGel powder and mixing it with Silicone - and having a super thin, flexible material, such as D3 - which has a melting point of 134c/273f.... So - mixing aerogel with D3 as a gasket would be good, and with D3 being a non-newtonian it works well for shocks. A space gasket as it were.

robomartin 3y ago

I can appreciate the thermal engineering that has gone into this. I have executed some extremely challenging thermal designs over time. They generally used heat transfer plates of the type shown in this video. My largest design as approximately 23 x 12 inches. Maintaining thermal efficiency and uniformity across the entire surface is where the real challenge lies. We had an extremely tight uniformity specification (0.1 deg C). This could only be achieved through a complex design process that entailed writing genetic algorithms to evolve and test solutions using FEA. In the end it was a combination of sophisticated impingement cooling and other techniques that did the job. That project was seriously challenging. I like projects that absolutely kick my butt. This one definitely did.

allenrb 3y ago
Can you share anything more about the project? This sounds fascinating.
- robomartin 3y ago
  Sadly, I can't share details or the application domain. I can tell you that we worked very hard to try and see if we could accomplish the objectives using forced air (fans). That effort involved laser-welded fins with sophisticated airflow management, techniques to break-up the boundary layer (which impedes optimal heat transfer) and powerful centrifugal fans. It worked well, yet it was large and sounded like a jet engine. Ultimately, while still complex, fluid-based thermal management offered a far more compact solution that could exist in a room with people not having to wear hearing protection. In addition to that, with a fluid-based system you can move the hot side to a different room.
  - KMag 3y ago
    Very interesting, though a bit odd to contrast air cooling with fluid cooling, given it takes pretty extreme conditions for air to not be a fluid.
    - 3y ago

tomcam 3y ago

That's wild. Especially the rough similarity to an air-cooled 3 cylinder engine.