Fixes for two Windows 11 performance issues discovered at the beginning of October are now available for download. The bugs hindered the performance of some Ryzen CPUs after upgrading to Windows 11. AMD just put up an update on its knowledge base blog, flagging both items as "issue solved; solution available."
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"As of October 21, 2021: Windows 11 update KB5006746 fully resolves the performance impact of Issue 1 described in this article," reads the blog post. "AMD Chipset Driver 3.10.08.506 fully resolves the performance impact of Issue 2 described in this article. AMD has verified that the performance and behavior of compatible AMD processors are working as intended on Windows 11 subsequent to the installation of these updates. AMD and Microsoft recommend that users promptly install this update on affected systems."
Issue 1 was a problem with the measured and functional L3 cache latency nearly tripling on certain apps and games (meaning that the CPU was accessing its memory way too slowly). Issue 2 was with AMD's "Preferred Core" feature not working correctly. Preferred Core allows users to assign apps to the fastest core on the chip manually.
| Known Performance Changes | Impact |
|---|---|
| Measured and functional L3 cache latency may increase by ~3X | Applications sensitive to memory subsystem access time may be impacted. Expected performance impact of 3-5% in affected applications, 10-15% outliers possible in games commonly used for eSports. |
| UEFI CPPC2 ("preferred core") may not preferentially schedule threads on a processor's fastest core | Applications sensitive to the performance of one or a few CPU threads may exhibit reduced performance |
The updates come now after first appearing last week in the Microsoft Insiders build of Windows 11. So, it was only a matter of time before both fixes became available. These AMD bugs were just one of a handful of launch-day bugs users have encountered during the Windows 11 rollout. A fix was in the works as soon as Microsoft and AMD confirmed the issues.
The L3 fix should be available now as a Windows 11 software update under Microsoft Knowledgebase ID 5006746. Open up Windows Update, and you'll see it listed. The preferred core fix is available as an AMD Chipset Driver package update under version 3.10.08.506 within the Apps and Features interface of Windows 11.
