Discussion Speculation: Zen 4 (EPYC 4 "Genoa", Ryzen 7000, etc.)

[Vattila]

Except for the details about the improvements in the microarchitecture, we now know pretty well what to expect with Zen 3.

The leaked presentation by AMD Senior Manager Martin Hilgeman shows that EPYC 3 "Milan" will, as promised and expected, reuse the current platform (SP3), and the system architecture and packaging looks to be the same, with the same 9-die chiplet design and the same maximum core and thread-count (no SMT-4, contrary to rumour). The biggest change revealed so far is the enlargement of the compute complex from 4 cores to 8 cores, all sharing a larger L3 cache ("32+ MB", likely to double to 64 MB, I think).

Hilgeman's slides did also show that EPYC 4 "Genoa" is in the definition phase (or was at the time of the presentation in September, at least), and will come with a new platform (SP5), with new memory support (likely DDR5).

What else do you think we will see with Zen 4? PCI-Express 5 support? Increased core-count? 4-way SMT? New packaging (interposer, 2.5D, 3D)? Integrated memory on package (HBM)?

Vote in the poll and share your thoughts!

 

[moinmoin]

That and the CPU selection for AM5 will likely be limited to expensive high end models at the beginning. So anything budget will only be served by AM4 for some time to come anyway.

 

[igor_kavinski]

First 6 months, demand may also outstrip supply.

 

[Doug S]

The reason DDR5 prices are still so much higher than DDR4 is primarily due to its on DIMM PMIC which DDR4 doesn't have. Until the chip shortage that makes those PMICs scarce ends the price of DDR5 will remain high. The end of the chip shortage has been 12-18 months away for about 12 months now, so don't get your hopes up for reasonably priced DDR5 anytime soon.

And it may get even worse, as China appears to be losing its battle to achieve "zero covid". The largest container port in the world has been completely shut down for a month now and counting. Over 500 ships are floating out there waiting for it to resume operation, with more arriving every day. Rumors claim other areas (including Beijing) are instituting mass testing which is the typical prelude to full lockdown.

 

[soresu]

AMD is cooking up something special for DDR5. It is very likely Zen 4 is going to be the best gaming chip out there.

DirectStorage may significantly cut CPU use in gaming workloads, we have yet to see the impacts of this brought to bare.

 

[Ajay]

The reason DDR5 prices are still so much higher than DDR4 is primarily due to its on DIMM PMIC which DDR4 doesn't have. Until the chip shortage that makes those PMICs scarce ends the price of DDR5 will remain high. The end of the chip shortage has been 12-18 months away for about 12 months now, so don't get your hopes up for reasonably priced DDR5 anytime soon.

And it may get even worse, as China appears to be losing its battle to achieve "zero covid". The largest container port in the world has been completely shut down for a month now and counting. Over 500 ships are floating out there waiting for it to resume operation, with more arriving every day. Rumors claim other areas (including Beijing) are instituting mass testing which is the typical prelude to full lockdown.

Yet another reason that the supply chain needs to be diversified across more countries.

 

[gdansk]

DirectStorage may significantly cut CPU use in gaming workloads, we have yet to see the impacts of this brought to bare.

CPU throughput is still very important. Even simple examples of DirectStorage use thread pools to achieve good performance:

DirectStorage/README.md at main · microsoft/DirectStorage

DirectStorage for Windows is an API that allows game developers to unlock the full potential of high speed NVMe drives for loading game assets. - DirectStorage/README.md at main · microsoft/DirectS...

github.com

It's an improvement, but new games will take this extra CPU budget as the baseline soon enough. And I wonder if AMD's many medium cores is better or worse than Intel's hybrid approach.

 

[Doug S]

Yet another reason that the supply chain needs to be diversified across more countries.

I don't think anyone would disagree, but you can't undo 30 years of consolidation overnight. Especially not during a period of severe shortage and logistical hurdles.

 

[Ajay]

I don't think anyone would disagree, but you can't undo 30 years of consolidation overnight. Especially not during a period of severe shortage and logistical hurdles.

Oh, it's going to take years. But, there is not time to start like the present. That's all I meant.

 

[nicalandia]

Let's hope by the time Ryzen 6000 is rolling out, DDR5 prices are more palatable. It was frustrating for Broadwell-E and early Skylake owners to buy rather slow DDR4 and then want to upgrade again. But with how DDR5 6000+ performs, that probably won't be as big of a concern. I hope AMD is going to have nice high speed DDR5 support right out of the gate.

Ryzen 6000 are Zen3+ Based APUs with DDR5, Ryzen 7000 are the Zen4 variants, both will be AM5 CPUs

 

[A///]

Ryzen 6000 uses DDR5 which was his point. It doesn't matter which era of processor it is, it's the fact it was designed around DDR5 long before there was a pandemic would be my guess.

IMO buying a laptop with DDR5 will be a negligible experience given the price is rolled into one. I'm not sure if prebuilt desktops will move to DDR5 as quickly.

 

[jpiniero]

IMO buying a laptop with DDR5 will be a negligible experience given the price is rolled into one. I'm not sure if prebuilt desktops will move to DDR5 as quickly.

If DDR5 is the only option... that sort of makes it pretty simple.

 

[Ajay]

Ryzen 6000 uses DDR5 which was his point.

Oof, that's going to sting a bit. OEMs buy in bulk, but still have to absorb costs and price higher for scarce commodities. It will wack DIYers harder, but we probably won't see 6000 series CPUs in the DIY market for sometime, if ever. Anyway switching to the new AMD desktop platform later this year, will be an early adopter for a high performance platform, total systems costs are going to go up anyway. Pay to play is the norm here, though as DougS pointed out, the normal roll over period to plentiful, less expensive DDR5 will be taking longer than DDR3->DDR4 did.

 

[A///]

If DDR5 is the only option... that sort of makes it pretty simple.

Ryzen 6000 is using AM5 DDR5. Raptor Lake will still be able to use DDR4 on their mobile platform.

Oof, that's going to sting a bit. OEMs buy in bulk, but still have to absorb costs and price higher for scarce commodities. It will wack DIYers harder, but we probably won't see 6000 series CPUs in the DIY market for sometime, if ever. Anyway switching to the new AMD desktop platform later this year, will be an early adopter for a high performance platform, total systems costs are going to go up anyway. Pay to play is the norm here, though as DougS pointed out, the normal roll over period to plentiful, less expensive DDR5 will be taking longer than DDR3->DDR4 did.

OEMs will absorb and pass on the cost to the consumers. That's how things work now with this global pandemic. I've been paying more for everything for the last couple of years. I couldn't wait and ended up getting a newer Intel platform. I'm probably not going to upgrade to Zen 4 even if it's miles ahead because the new platform will have teething problems at first, doubly so because it's AMD. Zen 5 may be ideal, but yes, I'm not expecting amazing DDR5 kits for the current "performance" kits available now which are eye-watering to say the least.

 

[DrMrLordX]

Raptor Lake will still be able to use DDR4 on their mobile platform.

Assuming Z690 supports it correctly (which it may not, or not entirely), there will be some DDR4 desktop boards for it as well.

 

[Markfw]

Assuming Z690 supports it correctly (which it may not, or not entirely), there will be some DDR4 desktop boards for it as well.

I have a Z690 running DDR4 4000 at 3200.

 

[Mopetar]

Yet another reason that the supply chain needs to be diversified across more countries.

Everyone says this, but they're never willing to pay the extra cost associated with having local or regional manufacturers that can't lower their prices as much.

Most people don't know where their products come from in the first place, and many wouldn't care if they knew. If the few who might care, most will balk at any extra cost.

 

[A///]

I have a Z690 running DDR4 4000 at 3200.

I don't believe that's what he meant. I believe he was stating that it all hinges on Raptor Lake being able to work on Z690 running DDR4 memory. Intel has hinted that Raptor Lake will be supported, but obviously Z790 is where their main concern will be.

 

[Markfw]

I don't believe that's what he meant. I believe he was stating that it all hinges on Raptor Lake being able to work on Z690 running DDR4 memory. Intel has hinted that Raptor Lake will be supported, but obviously Z790 is where their main concern will be.

This is the Zen 4 thread. we need to talk about that, Not Raptor lake.

Edit: Yes I replied once about Z690 which is Intel, but lets get back to Zen 4.

 

[DrMrLordX]

I don't believe that's what he meant. I believe he was stating that it all hinges on Raptor Lake being able to work on Z690 running DDR4 memory. Intel has hinted that Raptor Lake will be supported, but obviously Z790 is where their main concern will be.

There's two outstanding issues:

1). Will Raptor Lake's memory controller support DDR4 at all? I'm guessing it will.
2). Will Z690 support the additional voltage rail for the e cores? That's 99.9999% unlikely, unless Intel goes with some kind of IVR on Raptor Lake.

At least with AM5/Zen4, you know exactly what you're getting into: new board, new RAM. No two ways about it.

 

[igor_kavinski]

2). Will Z690 support the additional voltage rail for the e cores? That's 99.9999% unlikely, unless Intel goes with some kind of IVR on Raptor Lake.

Can't the CPU just take the voltage from the mobo and split it on-chip?

 

[DrMrLordX]

Can't the CPU just take the voltage from the mobo and split it on-chip?

That would require something like an IVR.

 

[JoeRambo]

That would require something like an IVR.

It already does have quite some of them.

I think at some point some marketing moron came to engineering and asked to deliver more frequency to E-Cores. And that operating point then demanded more voltage and power than FIVR meant for E-Cores could deliver. So they routed it to VCCIA and said FIVR was left feeding E core L2 cache domains.
Should be real easy to fix in RPL.

But this thread is about Z4 anyway, so lets keep discussions where they belong.

 

[MadRat]

The name 'Zen' implies it goes with the flow.

I wonder if they detect the spaced used in L2 so that they can turn it on and off as needed. 64MB is nice and all, but if you are getting everything done in 8MB then perhaps you would target a design with flexibility to benefit from lower latency accesses. Being able to turn L2 on/off in stages would certainly also help you operate under tighter electrical ranges which could lower temperatures.

 

[Ajay]

The name 'Zen' implies it goes with the flow.

I wonder if they detect the spaced used in L2 so that they can turn it on and off as needed. 64MB is nice and all, but if you are getting everything done in 8MB then perhaps you would target a design with flexibility to benefit from lower latency accesses. Being able to turn L2 on/off in stages would certainly also help you operate under tighter electrical ranges which could lower temperatures.

Just running a modern operating system is going to fill your L2$. Never mind your apps.

 

[Panino Manino]

Zen 4 Server with 12 DDR5 channels?

https://industrial.apacer.com/en-ww/NEWS/What-Sets-DDR5-Memory-Modules-Apart--7-Key-Specification-Differences-of-Industrial-DDR5-RDIMM