AMD recently warned its users about potential performance downgrades after updating supported hardware from Windows 10 to Windows 11. According to the official data, on Windows 11, AMD systems experience significantly increased L3 cache delays, which cause performance dips in games and memory-sensitive applications up to 15%. AMD said a fix is coming this month, but it is not part of the first cumulative updates for Windows 11 that went out yesterday. In fact, those updates made things even worse, turning the situation from bad to ugly.
TechPowerUp has conducted a series of cache and memory tests on a computer with AMD Ryzen 2700X and a B450 motherboard. Typical latencies for the processor usually hit approximately 10ns (nanoseconds). Windows 11 kicked that value up to 17ns (+70%), hence performance dips. After installing the latest cumulative update for Windows 11, L3 cache delays skyrocket to a whopping 39ns, four times worse than normal.
Luckily, it should not take long before AMD and Microsoft begin rolling out proper patches to fix the crippled performance. AMD published an update regarding the upcoming fixes, claiming the needed patches will arrive next week. AMD has fixed the issue with CPPC (when a system detects and prioritizes the most powerful core in a CPU) and now plans to start rolling out a new driver on October 21. A fix for L3 cache latencies will arrive as a part of Windows updates on October 19.
"The CPPC issue has been resolved. The AMD driver power profile is in the release process and targeted for GA release on 10/21. If it is needed before GA, AMD can share the driver directly with customers upon request.
The L3 cache latency issue has been resolved by Microsoft. Microsoft plans to release the fix in their 10C Windows Update, which is targeted for 10/19."
If you have already updated an AMD-based computer to Windows 11, we recommend you avoid installing the latest cumulative updates. Learn how to pause updates in Windows 11 here and wait for AMD and Microsoft to fix performance issues on affected systems.
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