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!

 

[igor_kavinski]

Remember most of the AIOs used in testing were using 100% fan speed. That is simply not desirable in real life.

That may be a problem only with 24/7 workloads. Typical users may not be bothered by the 100% fan ramp up from time to time. 12900K/KS users are already accustomed to that.

 

[igor_kavinski]

I'm not sold on your conclusion.

I based my conclusion on just one benchmark and did say if this picture holds true in other benchmarks. We need a comprehensive power efficiency focused review involving lots of commonly used applications and benchmarks. I guess we have to wait for Chips and Cheese to deliver on that.

 

[Racan]

Energy efficiency results from Techpowerup

 

[naad]

I based my conclusion on just one benchmark and did say if this picture holds true in other benchmarks. We need a comprehensive power efficiency focused review involving lots of commonly used applications and benchmarks. I guess we have to wait for Chips and Cheese to deliver on that.

Computerbase has done 65-140W benchmarks of around 10 different tests, not much change, zen4 is an absolute efficiency monstrosity at anything under 9W per core (probably even more since I'm including the I/O die)

Also much saner temperatures at any ECO stop
Notice how the new boost (run to 95C) behavior only seems to be a thing at stock, but single threaded performance remains the same from 230 to 80W

 

[igor_kavinski]

Has any of the reviewers tested with AVX-512 OFF just to see if it affects thermals?

In Linux at least, turning off AVX-512 actually increases thermals!



I hope someone comes up with a really good explanation for that.

My own guess is that without AVX-512, the various execution units of the CPU get hammered hard, forcing the CPU to use max power in an effort to deliver the best performance with max boost. With AVX-512, the CPU doesn't need to boost way past its efficiency curve and manages to deliver the needed performance at lower boost clocks.

 

[StinkyPinky]

Some of these sites need to use an air cooler, not all of us like to use water.

 

[exquisitechar]

Pure perf is way more marketable than perf/watt, and worse

Sure, but they are getting a lot of bad publicity because of the high temperatures and how hard Zen 4 is to cool. I don't think the single digit % performance improvement is worth that.

 

[Exist50]

unlimited mode on 13900K will go to ~350W, talk about insane levels of power draw for "stock" chip

I don't think we've had any indication that that "unlimited mode" is anything more than manually increasing power limits, i.e. not stock behavior.

Right now, AMD and Intel seem to be aligned in prioritizing the last bit of performance over efficiency. Hopefully it at least ends the brand war slap fights over that detail.

 

[naad]

In Linux at least, turning off AVX-512 actually increases thermals!

View attachment 68133

I hope someone comes up with a really good explanation for that.

My own guess is that without AVX-512, the various execution units of the CPU get hammered hard, forcing the CPU to use max power in an effort to deliver the best performance with max boost. With AVX-512, the CPU doesn't need to boost way past its efficiency curve and manages to deliver the needed performance at lower boost clocks.

Read this

Zen4's AVX512 Teardown - mersenneforum.org

Zen4's AVX512 Teardown Hardware

www.mersenneforum.org

tl;dr is that the frontend has much less work to do with avx512, so that saves power. And since AMD's avx512 is "double pumped", it doesn't have that extra FMA port gimping clockspeeds and eating the power budget

 

[lolek86]

70-80 Watts at idle for 7600/7000 in first reviews. One would have thought experience with soc would bring something in modern clean sheet design AM5 but no...

Does anyone have a hunch if ecomode also helps with idle consumption or if B660 with less everything would bring it down?

 

[Abwx]

Sure, but they are getting a lot of bad publicity because of the high temperatures and how hard Zen 4 is to cool. I don't think the single digit % performance improvement is worth that.

The competing 12900K/KS have higher temp, so why is AMD s lower temp that a bad publicity..?..
Because of badmouthing here and there..?.

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

Ryzen 9 7950X & Ryzen 7 7700X im Test: Temperaturen und Kühlung / TJMax und Temperaturen unter Last / TJMax = 95 °C gilt auch für Zen 4

www.computerbase.de

 

[inf64]

I don't think we've had any indication that that "unlimited mode" is anything more than manually increasing power limits, i.e. not stock behavior.

Right now, AMD and Intel seem to be aligned in prioritizing the last bit of performance over efficiency. Hopefully it at least ends the brand war slap fights over that detail.

You might be right, but there was some talk on twitter that this will be a one button setting in bios. So users can just flip the switch and enjoy the "350W out of the box".

 

[nicalandia]

In Linux at least, turning off AVX-512 actually increases thermals!

That's Linux. Like 5% of these forums care about that OS... We want Windows Performance numbers

 

[krumme]

So the additional performance benefit is not without considerable cost in electric bills. That 5950X looks mighty tempting there. All alone on its hill of efficiency.

Looks like Zen 3 is still the undisputed efficiency champion for 24/7 DC workloads, if other CPU heavy calculations mirror these results.

No way. Stop that nonsense. Look at computerbase 65w numbers.

 

[Exist50]

You might be right, but there was some talk on twitter that this will be a one button setting in bios. So users can just flip the switch and enjoy the "350W out of the box".

Sounds like any other one-click overclock, and the mobo vendors have had stuff like that for ages.

 

[inf64]

I guess Zen 4 gets a bad rep due to "stock" PPT levels AMD set. The Eco mode and manual tuned results are really really good. This bodes extremely well for mobile chips (both Phoenix Point and Dragon Range).

Edit:

der8auer has some great results with de-lidding :

Temps went down by more than 20C with direct die cooling! Crazy stuff.

7900X with direct die cooling runs at 5.5Ghz all core stable with 75C lol.

 

[Hitman928]

I guess Zen 4 gets a bad rep due to "stock" PPT levels AMD set. The Eco mode and manual tuned results are really really good. This bodes extremely well for mobile chips (both Phoenix Point and Dragon Range).

Yeah, mobile is going to be complete domination for AMD. Server as well, but they've had a comfortable lead there already, though Zen 4 really leaves just about zero niche cases where Intel makes sense anymore in server (outside of availability of course).

 

[Exist50]

I guess Zen 4 gets a bad rep due to "stock" PPT levels AMD set. The Eco mode and manual tuned results are really really good. This bodes extremely well for mobile chips (both Phoenix Point and Dragon Range).

Yeah, anything at sane per core power levels is going to be awesome, and obviously completely dominant in MT. They just really stretched for that last 5%.

 

[nicalandia]

der8auer has some great results with de-lidding :

Can you post numbers please? Currently I can't access Youtube

 

[igor_kavinski]

zen4 is an absolute efficiency monstrosity at anything under 9W per core (probably even more since I'm including the I/O die)

Thanks for that graph! Zen 4 at 88W is a better monster than 5950X

 

[DiogoDX]

Can you post numbers please? Currently I can't access Youtube

 

[naad]

These power figures make me very happy as an AMD shareholder.

 

[inf64]

Can you post numbers please? Currently I can't access Youtube

Here is a summary (from my edit):
"
Temps went down by more than 20C with direct die cooling! Crazy stuff.

7900X with direct die cooling runs at 5.5Ghz all core stable with 75C lol. "

 

[nicalandia]

Wow, That's impressive...!

 

[nicalandia]

These power figures make me very happy as an AMD shareholder.

I bought AMD Shares right after the Bulldozer Fiasco. I've been sitting them until now. I will wait until Zen5 and Sell.