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

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Vattila

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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).

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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! :)
 
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inf64

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We know clocks of the one chiplet CPU, we know, that they could not put cache chips on both chiplets to maintain lower thread count performance. We also know that 7800X3D is just 15% better than 5800X3D and most likely worse than 13900K in gaming. We also know that 7950X3D is probably somewhat better than 13900K in gaming.

I think we already know almost everything we need to know.

I do not see any crushing victory of the new AMD 3D chips, 7800X3D will be competitive with Intel in gaming only when you factor in the price of the CPUs, 7950X3D will probably trade blows with 13900KS, and if it still wins, only by a few percent.
13900K is just 6.1% faster than 5800X3D @ 1080p using the 4090 : https://www.techpowerup.com/review/rtx-4090-53-games-core-i9-13900k-vs-ryzen-7-5800x3d/2.html

7800X3D being 15% faster than 5800X3D should put it clearly ahead of 13900K and most likely the new 13900KS. Then, we have 7950X3D that will likely have a better boost on the 3D cache chiplet vs 7800X3D, so it should perform even better. So all in all, I'm not sharing the same opinion that 7950X3D " will probably trade blows with 13900KS, and if it still wins, only by a few percent.". It should be clearly a better gaming chip with decent performance advantage.
 

Timmah!

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13900K is just 6.1% faster than 5800X3D @ 1080p using the 4090 : https://www.techpowerup.com/review/rtx-4090-53-games-core-i9-13900k-vs-ryzen-7-5800x3d/2.html

7800X3D being 15% faster than 5800X3D should put it clearly ahead of 13900K and most likely the new 13900KS. Then, we have 7950X3D that will likely have a better boost on the 3D cache chiplet vs 7800X3D, so it should perform even better. So all in all, I'm not sharing the same opinion that 7950X3D " will probably trade blows with 13900KS, and if it still wins, only by a few percent.". It should be clearly a better gaming chip with decent performance advantage.

I dont think this is neccesarily the case. Actually, its IMO more likely that the 3d cache chiplet of 7950x3d will have the same boost as 7800x3d.
 

Abwx

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Apr 2, 2011
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Why AMD did not compare 7800X3D to 13900K then? I mean what better message could they send than that?

Because they did put the lights preferably on the 7950X3D, otherwise there s slides that allow to have an idea of the 7800X3D perfs.

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22-1080.2ee646a0.jpg


 

poke01

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We know clocks of the one chiplet CPU, we know, that they could not put cache chips on both chiplets to maintain lower thread count performance. We also know that 7800X3D is just 15% better than 5800X3D and most likely worse than 13900K in gaming. We also know that 7950X3D is probably somewhat better than 13900K in gaming.

I think we already know almost everything we need to know.

I do not see any crushing victory of the new AMD 3D chips, 7800X3D will be competitive with Intel in gaming only when you factor in the price of the CPUs, 7950X3D will probably trade blows with 13900KS, and if it still wins, only by a few percent.
Are people forgetting efficiency?

If Intel needs 350watts to achieve that then that's not a win!
 

Timmah!

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Jul 24, 2010
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We know clocks of the one chiplet CPU, we know, that they could not put cache chips on both chiplets to maintain lower thread count performance. We also know that 7800X3D is just 15% better than 5800X3D and most likely worse than 13900K in gaming. We also know that 7950X3D is probably somewhat better than 13900K in gaming.

I think we already know almost everything we need to know.

I do not see any crushing victory of the new AMD 3D chips, 7800X3D will be competitive with Intel in gaming only when you factor in the price of the CPUs, 7950X3D will probably trade blows with 13900KS, and if it still wins, only by a few percent.

As i said, we dont know what will happen when you will want to run app that is more frequency than cache-sensitive. Will it run on the second non-cache die? Cause if not, that 5,7GHz is boost is there just a hypothetical number, in reality you wont never see it - cause low-threaded stuff will run on primary v-cache die, all core loads you wont see 5,7GHz (i presume).
Additionally, if the second non-vcache die can boost to 5,7, does it mean its of higher quality than the second die in vanilla 7950x? Can all the cores in 7950x boost to that speed, or just bunch of the best ones (which are then by default chosen to be loaded in lower-threaded load scenarios.)

Yes, we can infer that all the CPUs will be probably within 10~15 percent on average of each other, depending on the usage, so in a way, whichever you get, you will be more than OK, its not like there will be 50 percent differences. Still, if i am interested in details, or if i really want to choose the perfect CPU for me, there are indeed questions unanswered.
 

KompuKare

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Jul 28, 2009
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I do not see any crushing victory of the new AMD 3D chips, 7800X3D will be competitive with Intel in gaming only when you factor in the price of the CPUs, 7950X3D will probably trade blows with 13900KS, and if it still wins, only by a few percent.
Another question is, will 7800X3D perform well with cheaper memory like 5800X3D does?

Not everyone wants to buy the really expensive top DDR5 nor tune it. That was a big advantage of the current 5800X3D (that and AM4 compatibility).

For the dual CCD 3D chips; well they probably do require fast memory or else what happens to threads on the 3D cacheless CCD when they have to go to main memory.

Both Intel and AMD really need some easy to use per-application config file with presets where they provide the best defaults for their CPUs in terms of which type of core (in Intel's case) or which CCD (in AMD's case) a program and it's threads should run on.
 

inf64

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Why AMD did not compare 7800X3D to 13900K then? I mean what better message could they send than that?
Because they compared 8C previous gen vs 8C next gen to show the gains? I have no doubt that 7800X3D will be faster gaming chip than 13900K(S).
This slide is different than what was shown in presentation.
Different set of games in the two slides.
I dont think this is neccesarily the case. Actually, its IMO more likely that the 3d cache chiplet of 7950x3d will have the same boost as 7800x3d.
I doubt that, but let's see. 5800X3d had a max boost clock penalty of ~5% vs 5800X. For 7800X3D it's 7.4% vs 7700X. If similar is true for 7950X3D, 7950X3D could have ~5.2Ghz boost on the Vcache chiplet.
 

Kocicak

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As i said, we dont know what will happen when you will want to run app that is more frequency than cache-sensitive. Will it run on the second non-cache die? Cause if not, that 5,7GHz is boost is there just a hypothetical number, in reality you wont never see it - cause low-threaded stuff will run on primary v-cache die, all core loads you wont see 5,7GHz (i presume).
Additionally, if the second non-vcache die can boost to 5,7, does it mean its of higher quality than the second die in vanilla 7950x? Can all the cores in 7950x boost to that speed, or just bunch of the best ones (which are then by default chosen to be loaded in lower-threaded load scenarios.)
I believe that the threads must be primarily assigned to die with cache for game threads and to bare die with other application, this does not seem difficult to do for me, but I know nothing about inner workings of an operating system, I wonder if AMD is working on some Windows update with Microsoft.
 

inf64

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I believe that the threads must be primarily assigned to die with cache for game threads and to bare die with other application, this does not seem difficult to do for me, but I know nothing about inner workings of an operating system, I wonder if AMD is working on some Windows update with Microsoft.
They were working with various software vendors, Microsoft included. Here is the PCworld video with more details:
 
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Timmah!

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I doubt that, but let's see. 5800X3d had a max boost clock penalty of ~5% vs 5800X. For 7800X3D it's 7.4% vs 7700X. If similar is true for 7950X3D, 7950X3D could have ~5.2Ghz boost on the Vcache chiplet.

We dont know if the 5GHz boost on 7800x3d is cause of product segmentation or because v-cache related limitation. If its cause of v-cache, i think its pretty possible same limitation will concern 7950x as well.
But as you say, we shall see. I am curious, how it all plays out, no doubt.
 

Abwx

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This slide is different than what was shown in presentation.

Whatever, according to Computerbase games tests, wich are somewhat favourable to Intel, the 13900K has 15% better perf than the 5800X3D.

So with 20% improvement the 7800X3D should be faster than the former, and that s with a 5GHz limited chip, that s quite low given that at 5.4GHz a single 7700X core use only 28W in Cinebench wich is a more demanding load than games, possibly that they want the 7900X3D/7950X3D to look better than the lower priced part.
 
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Timmah!

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I believe that the threads must be primarily assigned to die with cache for game threads and to bare die with other application, this does not seem difficult to do for me, but I know nothing about inner workings of an operating system, I wonder if AMD is working on some Windows update with Microsoft.

But does not operating system assign the threads? And Windows is historically pretty lousy at that. It may sound pretty straightforward in theory, but it can be completely different thing in practice. I would be bit cautious here.
 

In2Photos

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They were working with various software vendors, Microsoft included. Here is the PCworld video with more details:
Thanks for the video. Answered some of the questions we have been asking. The fact that they didn't give a price is odd. I hope they are not waiting to see the public's response to determine where to price it.
 
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Kocicak

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The fact that they didn't give a price is odd. I hope they are not waiting to see the public's response to determine where to price it.
It is in line with what I wrote, some of the 3D CPUs are probably not clearly winning overall, but just in perf/price ratio compared to Intel CPUs, so once it is clear how 13900KS performs and how much it costs, they will determine the price so that their products make sense and will be attractive to customers with Intel offerings in mind.
 
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exquisitechar

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I think the X3D CPUs and a tuned 13900K will probably perform similarly on average, each having significant wins in different games depending on how much the extra cache helps. Hope the pricing is good. A sanely priced 7800X3D with average DDR5 would be a not-so-expensive way to get top gaming performance.
 

JM Popaleetus

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From the PCworld's video: no direct OC will be possible but AMD will support both PBO and curve optimizer on all 3 X3D parts. I guess with good cooling and undervolting, it will be possible to push the clocks a bit further, hopefully on the Vcache die as well.
I feel like...other than to try sub-ambient coolers, set WRs or simply just because, PBO+200 and undervolting is all you can really do on Ryzen 5000/7000 anyway.

The boost algorithm already has these chips so close to the limit. Maybe you can eek out an extra 1% fine tuning each core individually, but daily driving all core OCs are a thing of the past.
 
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deasd

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The differentiate CCDs inside Zen4 X3D is a much more interesting solution than any other big-little design, I never thought CPU could work like this way. The last question is if AMD could schedule both 3D and non-3D cores flexibly, game with cache-intensive code use 3D cores, and non-3D high-frequency cores kicks in while switching back to less cache-intensive situation.

It would be a surprise for me if the different frequency of both CDDs inside 7900X/7950X was already a well developed plan by AMD which would be used in Zen4 X3D. Just wow.
 

Kaluan

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I think the X3D CPUs and a tuned 13900K will probably perform similarly on average, each having significant wins in different games depending on how much the extra cache helps. Hope the pricing is good. A sanely priced 7800X3D with average DDR5 would be a not-so-expensive way to get top gaming performance.
This may come as a shocker to people, but you can tune Ryzen 7000 CPUs as well, and from what we've heard from the PCWorld video, 7000X3D won't have the same restrictions as 5000X3D anymore either.
Check Zen 4 builder's thread, particularly @Det0x 's results.

7700X is only 2-4% behind 13900K (haven't seen direct well done big game averages, but you can extrapolate based on stuff like Jarrod's or HUB's 13600K launch day and 7600X/7700X/13700K big-game-average head-to-heads).
If someone imagines 7000X3Ds will be only 5% (or slightly more) than their vanilla cohorts then IDK what to tell them, that's just crazy talk.