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Dual CCD Ryzen 5000 CPUs - how bad is latency penalty when threads cross over to other CCD - Is it a big concern for thread heaving games and others

Wolverine2349

Wolverine2349

Wolverine2349

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Like for gaming mostly but some productivity work that benefits from more cores?



Most games do not use many cores and most max out at 6-8 cores so they stay on one CCD. However in the rare games that do scale more, is it really bad if a thread gets caught on the other CCD?? Like a much bigger concern for 5900X than 5950X as there are 2 6 core CCDs and a game is much more likely to scale beyond 6 cores than beyond 8.



So is a single CCD 8 core much better or an Intel 12th gen 8 core with e-waste cores of course disabled in such situation?? Or has that beer fixed that crossing CCDs is minimal latency penalty in games if it happens??

Like could a game crossing over to the other CCX cause a bad FPS drop that causes a pause or lag?? Or is that not a concern anymore. I mostly game but the 5900X with extra cores is great for productivity tasks some of which I also do.


It mentions using Game mode on Ryzen processors offering more than 8 cores.

Someone had mentioned there is a 400% increase in latency if a game thread gets stuck on other CCD?? Is that true or is it minimal difference these days with Ryzen 5000??

News - AMD Zen 4 Ryzen 7000 Specs, Release Date Window, Benchmarks, and More

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It doesn't matter anymore.

The inter core latency was only a problem on ryzen 1000/2000 and the first Threadripper. With Ryzen 3000/5000 and Threadripper 3000/5000 it's no problem and games perform the same whether you disable CCX's or not - the issues were resolved partially by AMD and partially by Windows through better scheduling
 
Grim5 said:
It doesn't matter anymore.

The inter core latency was only a problem on ryzen 1000/2000 and the first Threadripper. With Ryzen 3000/5000 and Threadripper 3000/5000 it's no problem and games perform the same whether you disable CCX's or not - the issues were resolved partially by AMD and partially by Windows through better scheduling
Click to expand...


Awesome thanks so much. Someone defending the e-cores claimed that 5900X would be worse if a thread got stuck in another CCD as opposed to on an e-core claiming latency between CCDs which kind of scared me a bit. Though as you said that does not matter anymore as that latency has been fixed and all good cores can be effectively used whether it is on 1 CCD or the other. But something getting stuck on an e-core is bad not because of latency penalty crossing core clusters on Intel 12th gen but because e-cores are just limited and much weaker and ruin slower than rest of main P cores screwing Windows scheduler, and especially bad for gaming all around and lack the instructions sets games depend on it seems.
 
On each CCD there is a golden core and a silver core, but on nearly every 2 CCD Ryzen chip, the first CCD will be where the absolute best core is. Even if it's on the 2nd CCD, the point is when doing something like gaming primarily the best core, therefore its CCD, will be used. Games just do not use over 8 cores, let alone 16, and probably won't for the foreseeable future. Frequency is still king with gaming.

If you're not buying a 5800X3D, a 5900x or 5950x is still the best to buy. Properly tuned (PBO), either of these processors will be the best for gaming outside of the X3D chip and they'll have the benefit of longevity at handling multicore tasks for years to come with ease. If you're on a tighter budget then a single CCD chip will still be great for gaming.

In terms of latency in general on AMD, it's much more important to buy the best RAM you can and then spend weeks tweaking it to its limit

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My 5900X is a beast for gaming oand workloads. Best of both worlds. I don't see any latency issues in either gaming or working, when using it.
 
Dual ccd are not problems, unlike Intel-s P + E cores which causes regression when data is moving from P to E cores, that's why for gaming it is best to turn off E cores.
 
The Rzen 5800X has one CCD while the 5900X has two.

Look at gaming reviews, there is not a single instance where the 5900X falls behind the 5800X, not one.

This CCD latency thing is just not a thing, not with Ryzen 5000 CPU's.
 
humbug said:
Look at gaming reviews, there is not a single instance where the 5900X falls behind the 5800X, not one.
Click to expand...
Not entirely true
You can spot several cases here https://www.techpowerup.com/review/amd-ryzen-7-5800x3d/15.html
(compare 5800X and 5900X, ignore 5800X3D, took this review because recent and convenient)
5800X wins Cyberpunk, Doom, Far Cry 5, RDR2
5900X wins BF V, Borderlands, Civ VI , CS:GO, Metro, SOTR
of course differences are small either way to call most of these a draw

5900X is helped by 100MHz higher boost clocks, 5800X by unified cache and higher power budget (higher multicore boost in some cases)
 
alec said:
Not entirely true
You can spot several cases here https://www.techpowerup.com/review/amd-ryzen-7-5800x3d/15.html
(compare 5800X and 5900X, ignore 5800X3D, took this review because recent and convenient)
5800X wins Cyberpunk, Doom, Far Cry 5, RDR2
5900X wins BF V, Borderlands, Civ VI , CS:GO, Metro, SOTR
of course differences are small either way to call most of these a draw

5900X is helped by 100MHz higher boost clocks, 5800X by unified cache and higher power budget (higher multicore boost in some cases)
Click to expand...
Difference is between 1 and 4 FPS, almost non-existent.
 
alec said:
Not entirely true
You can spot several cases here https://www.techpowerup.com/review/amd-ryzen-7-5800x3d/15.html
(compare 5800X and 5900X, ignore 5800X3D, took this review because recent and convenient)
5800X wins Cyberpunk, Doom, Far Cry 5, RDR2
5900X wins BF V, Borderlands, Civ VI , CS:GO, Metro, SOTR
of course differences are small either way to call most of these a draw

5900X is helped by 100MHz higher boost clocks, 5800X by unified cache and higher power budget (higher multicore boost in some cases)
Click to expand...

I'll give you Farcry 5 at 149 FPS vs 144 FPS

But the rest there is less than 1 FPS Difference, while even if the 3% difference in Farcry 5 is down to CCD latency i would still say AMD have entirely eliminated it, its so small a difference and so rare its just not really a thing. :)
 
alec said:
Not entirely true
You can spot several cases here https://www.techpowerup.com/review/amd-ryzen-7-5800x3d/15.html
(compare 5800X and 5900X, ignore 5800X3D, took this review because recent and convenient)
5800X wins Cyberpunk, Doom, Far Cry 5, RDR2
5900X wins BF V, Borderlands, Civ VI , CS:GO, Metro, SOTR
of course differences are small either way to call most of these a draw

5900X is helped by 100MHz higher boost clocks, 5800X by unified cache and higher power budget (higher multicore boost in some cases)
Click to expand...

Yup.

On top of this 5800x tends (not always) to get a better set of 8 cores, the chips on the 5900x after all are cut down so something wasn't quite right in the manufacture. From what I've seen 5900x can have some "ropey" cores that obviously still good enough to make the grade.

Which means the 5800x tends to overclock better.

So get a stronger single core and multiple core results, and a game won't use more than 8 so no benefit or the added cores on a 5900x.

Add to that a 5800x is cheaper, don't forget that.

Yes the 5900x has the higher base clock.

But the second you use any kind of productivity software that uses the extra cores it blows the argument out of the water, and as others have said the difference is so marginal.
 
alec said:
which in another context would be quite disappointing for 5900X having 50% more cores AND higher clocks AND double L3 cache ;)
Click to expand...

Its 100Mhz out of around 5000Mhz, and from the games perspective the 5900X doesn't have any more cache than the 5800X, each CCD has its own 32MB L3, that is why the Ryzen 9's have 64MB, its two CCD's, the game only sees one CCD for any workload at a time, it will switch between them but for whatever its doing in that at the time it only sees 32MB.
 
That's why they don't behave like the 5800X3D ^^^ ok its 64MB not 96MB but its still apparently 64MB, double. No its 32MB.
 
but but ... futureproof? :o
(I do remember weighing all these arguments with myself at Zen3 release. Trickier to make the decision based only on release day reviews. Still think 5800X was the right way to go for gaming, especialy with some PBO/curve optimiser added)

To stay on topic - inter CCD latency is the main reason why 5900X advantages over 5800X are not that apparent in games.
EDIT: And the latency is also small enough to not tank the performance
 
alec said:
but but ... futureproof? :o
(I do remember weighing all these arguments with myself at Zen3 release. Trickier to make the decision based only on release day reviews. Still think 5800X was the right way to go for gaming, especialy with some PBO/curve optimiser added)

To stay on topic - inter CCD latency is the main reason why 5900X advantages over 5800X are not that apparent in games.
Click to expand...
Nope, the only reason is because games doesn't utilize more than 8 cores, if games start to utilize 8+ cores properly then 5900x will have advantage.
 
alec said:
but but ... futureproof? :o
(I do remember weighing all these arguments with myself at Zen3 release. Trickier to make the decision based only on release day reviews. Still think 5800X was the right way to go for gaming, especialy with some PBO/curve optimiser added)

To stay on topic - inter CCD latency is the main reason why 5900X advantages over 5800X are not that apparent in games.
Click to expand...

The 5800X is the better choice for a pure gamer than the 5900X because its cheaper and you don't need the extra 4 cores, i'll agree with that.

To stay on topic - inter CCD latency is the main reason why 5900X advantages over 5800X are not that apparent in games.
Click to expand...

Wait, what? You just contradicted yourself, what advantages? 100Mhz higher clock? I can match that in literally 2 clicks in the BIOS.

Its not better because it doesn't have any.
 
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