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AMD Posts Official Fix for Windows 11 Bugs (Update: Microsoft Releases Patch, Too)

Lisa Su holding a 3D-stacked Ryzen 9 CPU
(Image credit: AMD)

Update 10/21/21 10 am PT: Microsoft has now released the Windows 11 patch to the general public. This patch contains the fix for the second bug that cause the L3 cache latency and bandwidth issues. That means that both required fixes are now available for AMD processors. We have amended the text below and added the relevant line from the Windows changelog to the end of the article. 

AMD has also confirmed to Tom's Hardware that it has released a patch for one of the two bugs that lead to reduced performance in Windows 11 and impact the Best CPUs for gaming. The first patch comes from AMD in the form of a chipset driver that fixes the UEFI CPPC2 driver that's responsible for steering threads to the correct cores. Naturally, all users on Windows 11 platforms should update to the new patch immediately — you can find the new driver here. The second patch comes from Microsoft as a Windows update that arrived today. As a reminder, the bugs impact all Windows 11-compatible AMD processors. 

The first patch fixes AMD's UEFI CPPC2 (Collaborative Power and Performance Control 2) feature, also known as the 'preferred core' technology that helps steer lightly-threaded work to the fastest cores on the chip. This bug primarily impacts performance in lightly-threaded applications. AMD says the performance reduction may be more noticeable in chips with more than eight cores and a >65W TDP rating, but the patch released today will correct those issues. We have the changelog listing below. 

The second patch, which Microsoft has released as the 22000.282 (KB5006746) Windows 11 update, fixes an L3 cache error that impacts latency and bandwidth. As you can see from our deep-dive testing last week, we found that, before the fix, AMD's L3 latency can be as much as six times higher in Windows 11 compared to Windows 10. Additionally, L3 bandwidth can be up to 12X higher in Windows 10.

AMD says the L3 cache bug can reduce gaming performance by up to 15% in some eSports titles and 3-5% in desktop PC applications, though we didn't see such a severe impact in our own gaming tests. Microsoft originally released the new Windows Update to its Insider program, but it is now available to the general public through the standard update process. Here's AMD's graphic that explains both patches:

AMD Windows 11 Bug Fix

(Image credit: AMD)

The bugs couldn't come at a worse time: Intel is on the cusp of launching its seemingly potent Alder Lake chips that will undoubtedly tighten the race for desktop PC supremacy. Making things worse for AMD, Windows 11 has new scheduler optimizations specifically for Alder Lake, so reviewers will use the new operating system for testing. That raised concerns that the bug could possibly result in unfair comparisons, particularly if the second patch didn't arrive in time for reviewers to incorporate into their launch-day testing for Alder Lake. The availability of both patches allays those fears. 

Both bugs impact every Ryzen CPU supported in Windows 11. That means all Zen+, Zen 2 and Zen 3 CPUs that comprise the Ryzen 2000, Ryzen 3000, Ryzen 4000, and Ryzen 5000 processors. In addition, select AMD EPYC processors for data centers and some newer Athlon chips are also impacted. 

As mentioned, we've already shared plenty of performance testing that shows the impact of the Windows 11 bugs. We'll circle back with updated testing soon.

Here's the AMD and Microsoft changelogs on the respective updates:

AMD Chipset Version 3.10.08.506 Changelog:

  •    AMD Chipset Drivers
            AMD Ryzen™ Power Plans (required for UEFI CPPC2 support with “Zen+” and “Zen 2” in Windows® 11)
            AMD Ryzen™ Power Provisioning Package (required for UEFI CPPC2 support with “Zen 3” and later in Windows 11)

Microsoft Windows 11 22000.282 patch (KB0006746) Changelog:

  • Addresses an L3 caching issue that might affect performance in some applications on devices that have AMD Ryzen processors after upgrading to Windows 11 (original release).
  • You can see more of the changelog here
Paul Alcorn

Paul Alcorn is the Deputy Managing Editor for Tom's Hardware US. He writes news and reviews on CPUs, storage and enterprise hardware.

  • husker
    Apparently, the only person with an AMD processor on the Windows 11 development team is kept deep in the basement, given a can of raid to assist with the roach problem, and is only still being paid because of a "glitch" in the system.
    Reply
  • TinyFatMan
    Wintel strikes back?

    Without wishing to be accused of being paranoid or conspiratorial, it is "strange" that Windows 11 only affects AMD's CPUs.
    We know the "alliance" has existed for a long time between Microsoft and Intel, so it seems "a little" fishy.
    Especially since Intel is releasing its new generation of CPUs!
    Reply
  • ern88
    I want to know where MS's WU is. It was released to preview channel. And thought it would have been out Tuesday. Although looking at AIDA64 benches. I think MS had more work to do with it WRT the read, write and copy speeds on L3. Although the latency issue looked resolved.
    Reply
  • VforV
    Now all MS has to do is drag it a little more with the patch, until after the Alder Lake reviews, just so all the "Destroys/Smashes/Obliterates" click bait titles for Alder Lake performance leaks, come true vs Zen3.
    Reply
  • Ubersoldat19
    This is as much on AMD as it is on Microsoft. They should be working together to verify stability and performance ahead of the Windows 11 "launch".

    Good to see that they are both getting the update out quickly, however.
    Reply
  • wifiburger
    installed this chipset driver + had the L3 fix KB already

    There's still issues with L3 bandwidth, it's all over the place 200Gb/s-400Gb/s not 1000Gb/s like Windows 10

    Considering this is ongoing for months now, I think Intel / MS are doing it on purpose.

    It almost feels like MS / Intel scheduler is not using the entire size of the L3 on AMD systems; just in time to screw with new v-cache from AMD !
    Reply
  • drtweak
    Wonder how it affects First Gen and bulldozer. Office PC is a 1600 and tech bench PC is a 8320. The 8320 has Win 11 on and a Win 11 VM on the 1600.
    Reply
  • hotaru.hino
    The major problem here is AMD still has to support Microsoft for issues relating to their processors. I don't know how much support AMD actually provides to other developers, but considering how much they really push for community support and how relatively smaller they are when compared to Intel or NVIDIA, I can't imagine they have a lot of resources to throw around to provide said support.

    But it's also funny how if AMD is slower, it's a conspiracy that their competitor is gimping them. But when AMD is faster, nobody bats an eye.
    Reply
  • -Fran-
    hotaru.hino said:
    But it's also funny how if AMD is slower, it's a conspiracy that their competitor is gimping them. But when AMD is faster, nobody bats an eye.
    No, Intel marketing discredits the benchmarks they were praising previously and the sheep follow suit :D

    It swings both ways really. You always have to read the fine print.

    As for the "conspiracy" here. As much it amuses me, it's stupid to think in such a thing.

    Remember: "never attribute to malice that which is adequately explained by stupidity". Or, in this case, a bit of incompetence from both AMD and Microsoft for not catching such a thing while working on the Kernel for Win11. What I do think about that is the time given to AMD to check and their constraints may have put them way behind schedule. Proof of that is they knew about most of the issues and were really forthcoming about them, no?

    Regards.
    Reply
  • epobirs
    TinyFatMan said:
    Wintel strikes back?

    Without wishing to be accused of being paranoid or conspiratorial, it is "strange" that Windows 11 only affects AMD's CPUs.
    We know the "alliance" has existed for a long time between Microsoft and Intel, so it seems "a little" fishy.
    Especially since Intel is releasing its new generation of CPUs!
    Nothing strange at all. AMD engineers are deeply involved with the HAL for AMD CPUs and most of the chip set driver work happens at AMD, not Microsoft. This is every bit as much AMD's screwup, if not more.
    Reply