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!

 

[LightningZ71]

Doesn't the cIOD already support x4x4x4x4 bifurcation of the "GPU" PCIe lanes?

And for NVME fanout: ASMedia Promontory 21, also known as AMD B650, can already be cascaded 1+1 (also known as AMD X670), which gives up to 20 fanout lanes (minus up to 8 SATA lanes) plus a bunch of USB ports. If four B650s could be combined into a 1+3 tree, you'd get 36 fanout lanes (minus up to 12 SATA lanes) plus more USB ports than any server needs. The performance loss due to the PCIe cascade might be a tolerable compromise for entry level servers.

It supports the fanout, but, it appears that some mobos don't have that feature supported/implemented/exposed Some boards properly support the 4 slot NVME pass through boards, some don't.

 

[LightningZ71]

It's literally cheaper to get a threadripper 24-core + a 700 dollar motherboard, than a gen5 PLX

Eh, what's $748 between friends? (mouser quotes ~$746 for the PM50084B1 in small lots, no ideas on the PEX89088)

But, in bulk, that price should be sub $500. With higher end AM5 boards already in that range, that could work for the expected board price for a "server" class product for AM5.

 

[Joe NYC]

Phoronix did some testing of EPYC 4004 vs. Intel. Turns out, Intel can only compete with 6 core Zen 4

https://twitter.com/x/status/1792929758348550615

 

[Thunder 57]

One thing I noticed is that they seem to have priced them to push sales on the 12-core. Possibly they have excess 6-core dies, with both servers and most client users favoring 8-core dies?



The problem with this is that many important databases are sold on per-core licenses, where you pay for all the cores in the machine running it (and all the cores in your hot spare...), not just the ones that are actually enabled. Lack of a 8-core vcache option seems to be an actual oversight to me.

I think that's already been becoming the case. With 6 cores per CCD instead of 8 you are losing out on some of the advantages of the 8 core CCD. We already see where the 7900X3D does worse than the 7800X3D, and no longer holds a premium over the 7900X. Between those, I would probably go with the non-3D variant.

Right now it seems to really only effect games, but that could change. With a six core CPU it doesn't really matter, so those will stay around. I could see a world where 12 core variants fall out of favor completely though.

 

[jpiniero]

Phoronix did some testing of EPYC 4004 vs. Intel. Turns out, Intel can only compete with 6 core Zen 4

Oof, that's right. Xeon E usually has stuck to it's TDP and no higher. So no 255 W there.

Guess Intel's going to have to go back to Ol Reliable (bribes)

 

[Saylick]

Guess Intel's going to have to go back to Ol Reliable (bribes contra-revenue)

FTFY

 

[adroc_thurston]

Guess Intel's going to have to go back to Ol Reliable (bribes)

Intel does not have the FCF for anything like that.
It's a very poor company due to bad business and high capex.

 

[Joe NYC]

Intel does not have the FCF for anything like that.
It's a very poor company due to bad business and high capex.

Seems like a perfect storm for Intel.

The same companies that have been force-feeding the market Intel products (Dell, Microsoft Surface) are the same companies about to switch from force feeding Intel to force feed the QCOM Arm chips, at expense of Intel.

In China, 100% Intel Huawei that could only sell Intel has been cut off, benefiting other OEMs (Lenovo, HP) who sell more AMD.

100% Intel entry level server market all of the sudden has competition beating Intel hands down.

There are just very few or no Intel monopoly segments left for Intel to take profits from and use the proceeds to finance anticompetitive practices in other segments.

And this, just before AMD starts transition from Zen 4 to Zen 5 across the board in all segments at once.

 

[Shmee]

Do we know yet if existing AM5 boards will support these Epyc 4004 chips? I watched Ian's video, and it wasn't clear on this. Also, to my understanding, we don't know yet if the 3D cache variants have one or both CCDs with 3D cache. If they both have the 3D cache, that makes the 16 core very appealing. It would be great for gamers who want 3D cache and more than 8 cores.

 

[SteinFG]

Do we know yet if existing AM5 boards will support these Epyc 4004 chips?

Probably gonna be on case-by-case basis. Some Asrock-Rack B650 motherboards already have support

Also, to my understanding, we don't know yet if the 3D cache variants have one or both CCDs with 3D cache.

One CCD has V-cache, other doesn't

https://www.amd.com/en/products/processors/server/epyc/4004-series/amd-epyc-4584px.html

128MB L3 means 96MB+32MB

 

[Joe NYC]

XT?

https://twitter.com/x/status/1796589137119822184

 

[igor_kavinski]

I suspect these are old CPUs that AMD saved for later. Why give free perf when you can sell it later as a higher clocked SKU? Lisa is wiser than most people (including AMD users) want her to be

 

[Joe NYC]

@adroc_thurston suggested there may have been a stealth migration to N6.

 

[adroc_thurston]

@adroc_thurston suggested there may have been a stealth migration to N6.

TSMC already did that eons ago.

 

[Joe NYC]

TSMC already did that eons ago.

If it happened, was there really a shrink, or just using N6 class EUV equipment for some layers?

 

[adroc_thurston]

was there really a shrink

No.

or just using N6 class EUV equipment for some layers?

Yeah. Shorter cycle times.

 

[LightningZ71]

I'd be interested in seeing if anyone can manage notable all-core boost gains on these.

 

[MadRat]

Why do the progressive Zen4 releases on the AM4 platform only tease 5 GHz, but seem to avoid it? Zen4 is already approaching 6 GHz on AM5 with a significant memory edge. Just seems like an artificial limitation of the Zen4 on the AM4 platform.

 

[inf64]

Why do the progressive Zen4 releases on the AM4 platform only tease 5 GHz, but seem to avoid it? Zen4 is already approaching 6 GHz on AM5 with a significant memory edge. Just seems like an artificial limitation of the Zen4 on the AM4 platform.

Zen 4 on AM4 platform?

 

[igor_kavinski]

Zen 4 on AM4 platform?

He probably meant AM5 but hey, they just gotta pair the Zen 4 core with the appropriate IOD to make it work on AM4, no?

 

[biostud]

He probably meant AM5 but hey, they just gotta pair the Zen 4 core with the appropriate IOD to make it work on AM4, no?

If understand it correctly then zen 3 isn't competing with zen 4 production capacity as they are not the same node family (6/7nm) vs (4/5nm), while continuing producing zen 4 products will be in direct competition with zen 5, and will probably be made as long as there are a demand for them in the EPYC/Threadripper

 

[Abwx]

Looking at the numbers for Zen 4 at Computerbase i found a discrepancy in their IPC test at same frequency calculations wich they say are using a geometric mean.

Computing the numbers the 7700X has 5.26% better MT IPC than the 12900K and 10.5% better than the 5800X while Computerbase state that it s 2% and 12% respectively.

They also state that the 12900K has 10% better IPC than the 5800X while the geo mean is only 5.2%, indeed the 7700X being 5.26% ahead of the 12600K both cant have the same 10% difference with the 5800X.

If someone can confirm the numbers since such an error is not without consequences, the bar charts for MT IPC at 3.6GHz can be found here, beware that some charts are with higher being better while others have lower as being better :

AMD Ryzen 7000 im Test: So schnell sind 7950X und 7700X

AMD Ryzen 7000 ist da. Im ausführlichen Test treten Ryzen 9 7950X und Ryzen 7 7700X mit Zen-4-Kernen gegen Ryzen 5000 und Intel Core an.

www.computerbase.de

If i take the 9 percentages relatively to the 5800X i get for the 7700X :

(112 x 105 x 111 x 112 x 113 x 106 x 109 x 115 x 112)^(1/9) = 110.5

Now the 12900K relatively to the 5800X :

( 93 x 108 x 111 x 102 x 118 x 106 x 96 x 105 x 110 )^(1/9) = 105.2

And the 7700X relatively to the 12900K :

( 121 x 98 x 100 x 109 x 96 x 100 x 114 x 110 x 102 )^(1/9) = 105.266



Edit : In a way this mistake is very good news for Zen 5...