Intel CPU chip stacking and heat.

Kippa

Senior member
Dec 12, 2011
385
1
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I know that Intel have started to move to stacked chips on their CPU and am aware that they are worried about heat issues with stacking.

I was wondering what if instead of running cores at say 3Ghz and stacking on top of them, what if they could run the cores at say 200 Mhz per core but stack them a couple of hundred times. So instead of going for really fast cores at 3Ghz and stacking with heat issues, they stack hundreds if not thousands of cores at 200Mhz instead. Do you think that would be a viable alternative and a way to solve the heat issue with stacking chips?
 

LTC8K6

Lifer
Mar 10, 2004
28,523
1,565
126
I know that Intel have started to move to stacked chips on their CPU and am aware that they are worried about heat issues with stacking.

I was wondering what if instead of running cores at say 3Ghz and stacking on top of them, what if they could run the cores at say 200 Mhz per core but stack them a couple of hundred times. So instead of going for really fast cores at 3Ghz and stacking with heat issues, they stack hundreds if not thousands of cores at 200Mhz instead. Do you think that would be a viable alternative and a way to solve the heat issue with stacking chips?
My understanding was not that Intel was stacking CPUS, but kind of taking the CPU apart and stacking the parts.
 

Jism

Member
Feb 12, 2019
27
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Intel tried that, it's called the Phi. It's like a big chip with a dozen of smaller cores but it kind of flawed after release. They pulled the plug.

Having alot of slow cores seems logical but the way programmers tend to design programs are simply not ready for it. Look at the PS4's / Xbox CPU; a 8 core CPU running at 1.6Ghz and later versions up to 2Ghz. Even tho you have 8 smaller cores running at a lower speed, it was difficult for devs to get the best ouf of it. They would be better off with a 4 core / high speed instead of 8 core and lower speed.

The PS3's CELL cpu had one single core and 7 SPE's if i am not mistaken. The same problem. Many dev's coudnt figure out a proper way and it took the console's EOL to finally extract the best out of the thing.

To make life alot more easyer, ZEN2 seems to take place in the new PS5 with a Navi thats around the 1070 / 2070 mark.
 

IntelUser2000

Elite Member
Oct 14, 2003
6,270
905
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Intel tried that, it's called the Phi. It's like a big chip with a dozen of smaller cores but it kind of flawed after release. They pulled the plug.
The OP is not talking about putting many cores on one die, but many cores stacked vertically.

So instead of going for really fast cores at 3Ghz and stacking with heat issues, they stack hundreds if not thousands of cores at 200Mhz instead. Do you think that would be a viable alternative and a way to solve the heat issue with stacking chips?
No, because then you'll end up with a CPU that runs at 200MHz but with thousands of cores. We could barely take advantage of 4 cores, let alone a thousand.

It'll work, but it'll be so slow to be unusable even for average joes.

The only confirmed stacked product is Lakefield, which is aimed for the 3-5W TDP space. Because the power usage is low, the heat output is low and a stack is viable. Also, they are not stacking multiple compute(CPU/GPU) dies together, but the CPU/GPU is on one die, and you have slower ones like chipset on the bottom, and RAM above.
 

sxr7171

Diamond Member
Jun 21, 2002
5,066
29
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What I read about it is that it will be the future. I also read that they need to develop new cooling technology to do it.

I am totally speculating but I think it will have to lead to creative liquid channels or heat pipe style cooling inside the silicon die. The cpus would have to be shipped with a water block fused on top eventually. That thermal resistance at the die -> solder/tim -> IHS -> tim -> heatsink/water block has to be minimized.

With even a 9900k you can do crazy things like triple 360mm radiators and it makes no difference. The bottleneck is not at the radiator anymore. It’s at the die interface.
 
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DrMrLordX

Lifer
Apr 27, 2000
13,040
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I remember reading about using tiny TECs to remove heat at the transistor level years ago when people first started speculating about node slowdowns below 14nm (or so). We're still heading for 5nm without anyone deploying tech like that - yet. Foveros seems to cry out for tech like that, though. Downside is that TECs can be pretty flaky. They burn out without warning. And they need new materials aside from bismuth telluride.
 
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