Windows update brings more performance to countless AMD Ryzen PCs
The Windows 11 update KB5041587 has it all: many Ryzen users are getting a free generation upgrade, Ryzen 5000 included.
The 7000 and 5000 Ryzen also benefit from the Windows 11 update KB5041587.
(Image: c't)
Microsoft is now providing the Windows 11 update KB5041587 as standard on PCs with Ryzen processors. As a so-called cumulative update, it usually installs itself, even if the Windows 11 installation is not registered for the Insider program. KB5041587 improves the gaming performance of many Ryzen processors from AMD, especially from the Zen 3 generation, i.e. Ryzen 5000.
According to AMD, the update improves the jump prediction code of its own processors – the company does not provide more detailed information. However, the results are quite something: depending on the processor, there is an average increase of 5 to almost 20 percent, with outliers beyond that. In some cases, this corresponds to the increase in performance brought about by switching to a new CPU generation. Notebook processors also benefit from the patch.
(Image: heise online / mma)
CPU brake solved in games
With a Ryzen 7 9700X, for example, we measured an increase of 13 percent in the integrated benchmarks of the action role-playing game "Cyberpunk 2077": In full HD resolution (1920 × 1080 pixels) and ultra settings, the CPU with a GeForce RTX 4080 and 32 GB of DDR5-5600 RAM achieves an average of around 165 instead of 146 frames per second (fps). The 1-percent percentiles, i.e. the lowest frame rates in the 1-percent window, also increase from around 87 to a good 93 fps.
Similar values were found for Ryzen 9 7950X and Ryzen 9 5900X after the update. However, this reveals a problem, which is why it is difficult to make more precise statements about the performance gain: The Windows update KB5041587 only increases the frame rate if the CPU is actually the bottleneck. In 1080p resolution, however, the GeForce RTX 4080 graphics card is apparently already limiting performance after the update.
In 720p, the plus would be greater – the CPU loads remain the same in this resolution, but the graphics card then has less to do. But hardly anyone wants to play in this resolution these days. For users, this means that thanks to the update, the processors are fast enough for future, faster graphics cards without limiting the frame rates.
We did the counter-check in 4K resolution (3840 × 2160 pixels) or with GPU-hungry ray tracing graphics effects: The update does not increase the frame rates in this case.
Also, because all PC configurations behave differently, it is not possible to make any precise and generally valid statements. Except that Ryzen processors run faster in many games if the graphics card is not limiting. This is backed up by countless user reports, for example on Reddit, as well as tests on other websites.
Hardwareluxx, for example, also tested the popular Ryzen 7 5800X3D in seven games with 720p resolution and found an average increase of 17 percent. Many online games are difficult to test due to their dynamics, but can also benefit. For example, there are reports of significantly higher frame rates in "World of Warcraft".
Unnecessarily aggressive protection against side-channel attacks?
The actual cause of the slow CPU acceleration is not yet entirely clear. However, there are indications that it is ultimately about functions in Windows 11 that are intended to protect the system against Spectre-type side-channel attacks. These Spectre protection measures are intended, for example, to prevent malware from steering the CPU jump prediction in certain directions to read out the memory addresses of external processes.
However, jump prediction is an essential means of all modern processors to increase performance. The CPUs predict with a high accuracy rate which instructions will be required in the near future and load them into the cache in advance. In doing so, they create several branches with different instructions. If there is a correct one, it is used. This is where the name branch prediction comes from.
One of the anti-Spectre protection measures are so-called cache flushes, i.e. the complete emptying of the memory buffers for branch prediction during thread changes. This would explain why the KB5041587 update helps games, but not most applications. In the PCMark 10 application benchmark, for example, we measured no improvements with the Ryzen 7 9700X, Ryzen 9 7950X and Ryzen 7 5900X.
In games, CPUs execute a lot of different code; the instructions jump back and forth wildly. If you limit the jump prediction, the fps drops. In applications such as render programs, on the other hand, CPUs process a constant flow of similar instructions, so they are less reliant on prediction. The Ryzen 9000 in particular was able to deliver its promised performance in applications, and only looked unexpectedly poor in games.
It is questionable why neither AMD nor Microsoft have noticed this so far.
Conclusion: Install without fail
Anyone using a Ryzen processor in a Windows system should install Windows 11 with the KB5041587 update. Any gaming advantages that Windows 10 may have had are now gone. This applies in particular to Ryzen 5000 (Zen 3) and above.
Due to GPU limits, the advantages are not necessarily evident from the fps display. Due to higher minimum frame rates alone, however, we recommend the update – Games feel smoother this way.
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(mma)