AMD "Milan-X" Processor Could Use Stacked Dies with X3D Packaging Technology

[AleksandarK]

AMD is in a constant process of processor development, and there are always new technologies on the horizon. Back in March of 2020, the company has revealed that it is working on new X3D packaging technology, that integrated both 2.5D and 3D approaches to packing semiconductor dies together as tightly as possible. Today, we are finally getting some more information about the X3D technology, as we have the first codename of the processor that is featuring this advanced packaging technology. According to David Schor, we have learned that AMD is working on a CPU that uses X3D tech with stacked dies, and it is called Milan-X.

The Milan-X CPU is AMD's upcoming product designed for data center usage. The rumors suggest that the CPU is designed for heavy bandwidth and presumably a lot of computing power. According to ExecutableFix, the CPU uses a Genesis-IO die to power the connectivity, which is an IO die from EPYC Zen 3 processors. While this solution is in the works, we don't know the exact launch date of the processor. However, we could hear more about it in AMD's virtual keynote at Computex 2021. For now, take this rumor with a grain of salt.


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[KarymidoN]

Intel RN:
That glue is Illegal and i don't accept the result of this election #notmyglue #MakeProcessorsGreatAgain

Jokes Aside, looks cool i hope it doens't come at a latency cost or huge power draw/temps, but its for servers so they can figure it out a way to cool it.

 

[WhitetailAni]

That's cool.
I bet this is how we'll get 128+-core Threadrippers.
"Threadripper 6990X, 256 cores, 512 threads, up to 4TB of DDR5 RAM in 16-channel, PCIe 6.0, MSRP $6000"

 

[Punkenjoy]

Interesting, but i wonder how they will solve the cooling issue of these chips.


Do we will see actual high clock or it will be a 256 core/32 chiplets 1 GHz low voltage CPU. can't wait to see how this will behave. Even if this can be taken with a grain of salt, we will see stacked chips in the near future.

 

[Jism]

Interesting, but i wonder how they will solve the cooling issue of these chips.


Do we will see actual high clock or it will be a 256 core/32 chiplets 1 GHz low voltage CPU. can't wait to see how this will behave. Even if this can be taken with a grain of salt, we will see stacked chips in the near future.

It's stacked in such a way that all the heat transfers easily to where it should go. Not stick in that and burn any components around it.

They use traces to remove the heat from those area's. IBM did even experiment with such traces basicly providing watercooling on nm level.

Ofcourse you can go high clocks; it's just a bit of impossible task when working with 64 cores and beyond. For high clocks you need a less dense chip if you want to preserve power consumption and / or cooling.

 

[Chrispy_]

Laws of physics still apply so this approach will likely be limited by thermal density, but four stacked dies at 1GHz using 10-15W each rather than one 4GHz die running at 105W is still an improvement and for stuff that scales well with core counts there are no immediate downsides other than cost.

Ramping up clockspeed requires more voltage, and since the power is proportional to the scale of the voltage, a fast and narrow solution will always be less efficient than a (fully-utilised) slow and wide solution. That's Datacenter 101.

 

[Punkenjoy]

It's stacked in such a way that all the heat transfers easily to where it should go. Not stick in that and burn any components around it.

They use traces to remove the heat from those area's. IBM did even experiment with such traces basicly providing watercooling on nm level.

Ofcourse you can go high clocks; it's just a bit of impossible task when working with 64 cores and beyond. For high clocks you need a less dense chip if you want to preserve power consumption and / or cooling.

I have seen the patent on these technology. I am just not sure how close they are from mass production. Hope that you are right. But like Chrispy_ say, if they stack 4 10-15 watt chip, it's only 40-60 watt per stack. When we see what low power Zen APU and Apple M1 can do with such low TDP, they can probably do something powerful. Also, it would mean these chiplets are different than the one being used right now as they would need to interface from top and bottom.

but we will see, still unclear what these dies will be. It's not unlikely that wit would be HBM or something else.

 

[bob3002]

I remember seeing that image as part of a larger slide from this Anandtech article from last year.

That article seemed to refer to that diagram as four compute chiplets and the stacks being HBM memory, similar to a CPU version of the Vega/Radeon VII GPU designs. Cooling an HBM stack is probably less challenging than trying to cool a stack of CPU chiplets clocked to a high frequency.

Perhaps the HBM could act as a form of L4 cache, similar to what Intel did with Broadwell's eDRAM?

 

[ip2k]

That's cool.
I bet this is how we'll get 128+-core Threadrippers.
"Threadripper 6990X, 256 cores, 512 threads, up to 4TB of DDR5 RAM in 16-channel, PCIe 6.0, MSRP $6000"

What’s funny is that if they did launch such a CPU, they could probably get $60k for it and it would be price / perf / space competitive if they could make it work with not-too-exotic cooling that OEMs could easily integrate.

The latest greatest 40-core Intel® Xeon® Platinum 8380 Processor (60M Cache, 2.30 GHz) is $6743.00 MSRP, or $168.57/core. 9282 is $13012 for 56 cores ($232.35/core) but that’s a precious-gen product so forget it. 256 cores for $60k would be an easy sell for 2U2P and a game-changer for density. Doing it in 1U2P or smaller blade systems would be just incredible.

 

[R0H1T]

Ramping up clockspeed requires more voltage, and since the power is proportional to the scale of the voltage, a fast and narrow solution will always be less efficient than a (fully-utilised) slow and wide solution. That's Datacenter 101.

The frequency/voltage curve for Ryzen is usually optimal in the 2~3Ghz range, different chips can have slightly different curves depending on the binning. So no AMD can increase the clock speeds a fair bit above 1GHz, without increasing power consumption or heat too much, though I'm still skeptical about the rumor & don't see how Milan X is anything but vaporware btw what about everyone's favorite HBM

 

[Punkenjoy]

The frequency/voltage curve for Ryzen is usually optimal in the 2~3Ghz range, different chips can have slightly different curves depending on the binning. So no AMD can increase the clock speeds a fair bit above 1GHz, without increasing power consumption or heat too much, though I'm still skeptical about the rumor & don't see how Milan X is anything but vaporware btw what about everyone's favorite HBM

You are right about the 2-3 GHz range, my 1GHz was more as an exageration than a real point.

But i think this will happen in the near future. This is the next big thing. I do not thing we will see a Server CPU with HBM. But i could see a custom chips with as much as possible cores + HBM to be put in a HPC chip for a future super-computer doing massive AVX-512 calculation while remaining as power efficient as possible.