Windows 11. AMD multi CCD Memory and cache latency (Everything is running within spec)

1 : Anonymous2021/11/02 18:35 ID: qlaw1a

Hi Everyone,

After HardwareUnboxed video ( AMD Ryzen: Windows 11 vs. Windows 10, Faster Gaming Performance - YouTube ) I finally bit the bullet and clean installed windows 11. However, the tomshardware article ( Tested: AMD's Windows 11 Patch Wins Some, Loses Some | Tom's Hardware ( ) was still on my mind. Specifically, the chart ( oS2T7wrxSPMKRgXNY3F5EU-970-80.png.webp (455×344) ( ) which shows latency increase in 10MB to 32MB memory regions on Windows 11 when compared against Windows 10.

So, after I completed my clean full install of Win11, the first thing I did is, run latency tests for all relevant memory regions. As you will see when you go through the data, I am quite confident in saying that Tom's Hardware may have had a slight problem in their dataset, because my Win11 results are quite close their Win10 results for 5900x, and quite a bit better in the problem areas that they have shown from 10MB to 32MB in Win 11.

Please find the data below as my insight into this discussion. I personally can conclusively say that, cache latency is normal on Win11 now, even on multi CCD Ryzen CPUs.

I performed 7 runs, and graphed them out for your visual pleasure.

Raw Data


Additionally, all my 3D mark results have slightly improved, with game benchmarks still where they were in Win10, or slightly better.

I am sure there could be something that I may have missed, so please feel free to review and provide feedback as you deem necessary.

Thank you!!

EDIT: Grammar. And just as a quick clarification, my results for Win10 were in line with Tom's hardware, and did not feel the need to repeat the data here when I am already adding Tom's chart in here.

2 : Anonymous2021/11/02 19:22 ID: hj1rtkr

I am sure there could be something that I may have missed

Two points, without W10 results from your machine we cannot infer that everything is OK with your machine from 10-32MB (not saying it's wrong, just that this is an experiment without controls). Also Steve from HWU mentioned that when he swapped CPU there was a performance bug in Win11 that could only be solved by a clean install.

ID: hj1y07s

Thank you. This is a good point. I added the clarification. My results for Win10 were in line with Tom's hardware, and did not feel the need to repeat the data here when I am already adding Tom's chart in here.

As for the bug with CPU swap, that needs to be fixed, but it doesn't impact most of us, as we don't seem to change CPU models as often as reviewers.

I hope this helps.

ID: hj1y8g5

Ay, thx for the reply.

ID: hj21amy

This makes me wonder if I should upgrade my processor before going to Win11 (have a R7 2700X but considered something in the 5000 series)?

ID: hj4naof

I've heard now several times that with a clean install, the performance bug/hit/drop/whatever you want to call it wouldnt occur (as often) compared to a upgrade from windows 10...

I've upgraded my laptop (no clean install), but have hold back on my main desktop because of the mentioned issues. My laptop does not have a performance hit so far, memory latency seems within normal range as far as i can tell, but it was a pretty "clean" system before the upgrade without many things installed (~15 GB of data including programs)...

ID: hj5giat

Can you also comment on disk speed as well ? Is there any increase in your case as well esp in random ?

ID: hj6h45p

This is not only swaps, but any detection of a new cpu. For example, I reset bios and reseates the cpu as it came out with the heat spreader. The bug occurred after that. Of course, not a common thing, but it's more than just new cpu all together, but it's like it's applied to the exact hardware profile and not the system.

ID: hj4b1yx

well Windows used to do some optimisations based on your CPU/MB during installation

I'm guessing we're back to it, I'm quite surprised that some professional tech youtubers are surprised that they have to reinstall windows when they switch CPU (this was common practice at least up to Vista)

ID: hj4jomb

I think they were surprised since it hasnt been a thing since vista, so they expected it to work like the last 5 releases

ID: hj4fl0b

Also Steve from HWU mentioned that when he swapped CPU there was a performance bug in Win11 that could only be solved by a clean install.

Shit, sorry to bother you with this, but if you still remember the details was this in regards to doing an upgrade from 10 to 11, or swapping a cpu itself?

I've done an upgrade in place from 10 to 11 and didn't reformat. I know it would have been wise to, but I've been lazy.

On an x470 with up to date chipset and bios (Asus CH7) and a 5800x if that's relevant.

ID: hj4jqkz

Swapping CPU's on one install of win 11

3 : Anonymous2021/11/02 20:04 ID: hj1yacy

im glad the real experiences are finally being told. i knew i couldn't have been the only one who noticed an uplift with w11

ID: hj268yf

Nope. I noticed it as well, for my use cases, and that was before the latency issue fixes. Whatever the extra latency added, it wasn't more than what win11 improved. For me.

I applied the AMD cp

driver fixes, and the microsoft ones, and the latency in AIDA did go down, not that I noticed.

ID: hj59ihd

Isn't it safe to assume that the uplift came from a clean windows install?

4 : Anonymous2021/11/02 20:41 ID: hj246ra

I'm wondering if I should do the offered Win11 upgrade in place, or just nuke the OS drive and install from scratch.

ID: hj2a7kg

Nuking is usually always the right answer

ID: hj3n37h

I personally decided to do a fresh install. After quite a long time of installing/uninstalling things and just using my system (games), there was quite a bit of crud scattered about. Doing a fresh install cleaned all of that up for me.

Backup first!

ID: hj4u6eo

It's the only way to be sure

ID: hj2z1nd

I installed 11 yesterday and decided to format the whole drive, no problems yet except snipping tool breaking.

ID: hj3u5xl

Wait, is it actually a bug? I was about to clean install Windows 11 (currently use it from upgrading from Windows 10) because I can't use snipping tool.

ID: hj2v6db

Always nuke it, it's just not worth it doing the upgrade (Lots of potential issues, data trash lying around, ..).

On a SSD Windows installs in like 20-30 minutes tops.

My first plan was to do the upgrade, then nuke it (Just to be sure my license is upgraded), but it seems like any Windows 10 activation is also valid for Windows 11, so I'll probably just do a clean install.

ID: hj4xdq9

It's not about the OS installation, it's about the software and configurations that need to happen AFTER the OS installation.

ID: hj42hzy

You can update and it'll probably be fine. That said, nuking is usually just less potentially troublesome.

ID: hj2s5bx


ID: hj4bag0

Upgrade to get the free offer and then fresh install.

ID: hj4bs5a

I did the update in place when they offered the preview release. I started with the laptop since it's a Surface and it didn't have anything critical on it. It worked like a charm and I really like the new interface.

After a few days, I did the same with my 5900x desktop. It's good enough for now, but I'll be nuking it pretty soon. I'm keeping W11 though.

5 : Anonymous2021/11/02 18:36 ID: hj1knc1

I hope this helps all who were like me, and on the fence.

6 : Anonymous2021/11/03 01:16 ID: hj3922s

The memory latency that 99% of people heard of, used AIDA 64 to infer the test from..
Even tom's hardware used AIDA 64...

The L3 cache was never slower, it was smaller...
Windows11 can power down l3 cashe....

A reg key can be done to make windows recognize the changes..

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession Manager Memory Management

Modify "SecondLevelDataCache"
Add + Modify "ThirdLevelDataCache"

With both, use AMD site to determine the l2 + l3, and put values of mb with both Dwords as a decimal...

Performance should increase...

L3 is tied with memory, so you need to disable gear_down_mode on bios...

AIDA can't read l3 data values above a certain value, so it's test is inconclusive of l3 accuracy...

You should notice a big increase in performance.

Updating the os does net peformance increases with the L3 fix, but by so little, it's not even noticable..

That windows update L3 fix, was also tied with the CPPC fix as well, It was that CPPC fix that netted the biggest peformance.

ID: hj59x42

This is the comment that makes the most sense here. Have you found VBS and such to impact your performance though?

ID: hj59y01

This is the comment that makes the most sense here. Have you found VBS and such to impact your performance though?

7 : Anonymous2021/11/02 20:52 ID: hj25uji

I feel that Win 11 and Win 10 differences are well within the margin of error in performance now on the same hardware.

ID: hj2sc0v

Except for random read and write performance which has a huge uplift. Which is great for people who actually do work.

ID: hj42fjg

The problem is not that. But the mystery around the variables that affect performance.

VBS is still a huge question, and while this L3 bug has been fixed, the fact that it pops up again when changing CPUs shows there's still many, many things left to iron out.

ID: hj45f2j

True ... not unusual with a 'new' OS ... I remember when we used to wait for a SP before rolling it out.

8 : Anonymous2021/11/03 06:25 ID: hj496sk

Hardware Unboxed said there's still a huge latency bug when you swap CPU without a win11 clean install, might be that

9 : Anonymous2021/11/02 22:21 ID: hj2jml0

Not sure what software that is.

here's my 3900x on Windows 11 for cache & mem latency (sisoft sandra)

ID: hj2paps

I can make a graph of that, hold on a minute 🙂

10 : Anonymous2021/11/02 23:05 ID: hj2q2le

But remember guys... 12th gen intel is 50% faster than AMD!*

*when tested using Windows 11's last release before cache latency and performance fixes

ID: hj3bx1e

Lol what does intel have anything to do with this lol

ID: hj3elsd

Intel's Big Little design influenced Windows 11's Scheduler design.

ID: hj2r8dh

So now it's "only" 35% faster? Idk what the data is that Intel has though, could be something very fucking specific like they always do.

11 : Anonymous2021/11/02 22:59 ID: hj2p9ni

How did you measure it?

12 : Anonymous2021/11/03 00:48 ID: hj354h0

I have a 2700x with Win 11 installed and up to date. How do I find out if I'm affected by this? Everything seems to be running fine but I don't want to miss out on a free performance gain if I don't have to.

ID: hj4afyx

AFAIK, it affects people only on Ryzen 5000 CPUs.

ID: hj75ok0

AIDA64 is the primary tool being used to bench the L3. The problem does impact processors going all the way back to Zen1, and even some seemingly random intel processors. Zen+ doesn't have MBEC so it should also have VBS disabled.

13 : Anonymous2021/11/03 00:54 ID: hj35whv

Done a clean install on Windows 11, fully updated including all fixed and really happy with it

14 : Anonymous2021/11/03 03:40 ID: hj3t0y6

pretty sure they fixed the latency and there was a bandwidth issue still lingering or something but that might have been fixed by now too

15 : Anonymous2021/11/03 04:22 ID: hj3xygu

Compared to what ?

16 : Anonymous2021/11/03 10:43 ID: hj4rfoa

Awesome I might do a cyberpower amd/Nvidia build next spring. 🙂

17 : Anonymous2021/11/03 14:43 ID: hj5jefv

Yawp, I noticed my 3DMark numbers going up (especially the CPU profile test) going up by a few numbers as well...

19 : Anonymous2021/11/02 22:56 ID: hj2ot93

It’s always good to get external validation regardless of the reviewer. It also gives more credit to HUB (in this case) so everyone wins. More data is never a bad thing.


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