AMD has apparently addressed the inter-core latency issues of its Zen 5 “Ryzen 9000” CPUs, with major drops in inter-core latencies also resulting in extra performance.
AMD Quickly Addresses Ryzen 9000 “Zen 5” Inter-Core Latency Issues with AGESA 1.2.0.2 BIOS Firmware and Major Improvements
A few weeks ago it was reported that AMD was working on a patch to improve inter-core or core-to-core latencies for its newly released Ryzen 9000 “Zen 5” CPUs, as multiple tech sources found that latencies were suboptimal with latencies as high as 180-200 ns when two cores from different CCDs communicated with each other. This led to suboptimal performance and much worse results than those seen on Ryzen 7000 “Zen 4” CPUs.
It looks like AMD has fixed this intercommunication between cores and CCDs in their latest AGESA 1.2.0.2 BIOS update. ASUS has announced the first release of this particular BIOS and It is currently implemented on a variety of X670E, B650E and B650 motherboards. This means that PC users running any of the updated motherboards with the Ryzen 9000 chips can take advantage of the new BIOS and see notable gains.
Member of Anandtech Forum, Det0xmanaged to update his ASUS ROG Crosshair X670E Gene motherboard with the latest BIOS and posted results comparing the previous BIOS to the latest one using the CapFrameX core-to-core latency tool. The results are quite impressive. With the older BIOS, the user saw an average latency of 180 ns between CCDs and around 18-20 ns when cores communicated on the same CCD.
With the new BIOS, average latency drops by 58% to 75 ns when communicating between CCDs, and inter-CCD latency remains the same at 18 to 20 ns.
AMD Ryzen 9 9950X with AGESA 1.2.0.1A BIOS:
AMD Ryzen 9 9950X with AGESA 1.2.0.2 BIOS:
Now, inter-core latencies shouldn’t impact overall performance too much since AMD’s scheduler mainly takes advantage of the faster CCD for gaming applications, but in multi-threaded applications, it looks like the improvements from this AGESA 1.2.0.2 BIOS fix are quite substantial.
Users are reporting that they are getting up to 400-600 points improvement in Cinebench R23. Some users who own the Ryzen 9 9950X also report that CPU-z and 3DMark CPU benchmarks have seen notable improvements and the best part is that the BIOS runs perfectly without any issues.
Some interesting information was also shared by benchmark author Y-Cruncher, who claims that the latency issues were due to a change in Zen 5 tuning parameters. The changes were made because they were showing results in the workloads tested by the engineering team, but in synthetic benchmarks, they showed poor results, which is why AMD is now reversing its decision and releasing this new patch.
The author was surprised that the patch was released so quickly as the architects said it could take a while to be released due to validation, but it appears that ASUS has released the update and it works as expected to address the inter-core latencies.
This was faster than I thought. I think I can say that now that it happened. One of the lead architects told me that the latency regression was because they changed a bunch of tuning parameters for Zen5. It helped in whatever workloads they were testing, which is why they did it. But now that the benchmarks are out, they realized that the change looked really bad for synthetics. So they were going to revert it. But they said it would “take a while” due to validation.
Honestly, I didn’t think this would happen until a few months later.
Overall, this is great news for AMD Ryzen 9000 “Zen 5” CPU owners and the red team in general. Other manufacturers are expected to release their respective AGESA 1.2.0.2 BIOS updates later this month so we can see more users getting updated to the new firmware for a smoother and more stable experience with Zen 5 chips. The BIOS will also include the new “105W TDP” mode for the AMD Ryzen 7 9700X and Ryzen 5 9600X CPUs.
News sources: Anandtech Forums, Overclock.net Forums