Reintroduces C-State Boost Limiter with >4 Cores Loaded
Taken from TPU … AMD released the latest version of the AGESA microcode for Socket AM5 platform. The new version 188.8.131.52 most notably reintroduces a Precision Boost C-state limiter that [accidentally?] got removed with version 184.108.40.206. This limiter prevents the CPU cores from boosting above 5.50 GHz when more than 4 cores are active (i.e. experiencing heavy workload). SkatterBencher demonstrated how this affects performance on Ryzen 7000-series desktop processors.
NopBench, a utility developed by ElmorLabs, lets you figure out the maximum boost frequency obtainable as workload scales across available CPU cores (i.e. starting from 1-thread, to n-thread). NopBench invokes the NOP instruction, and measures the number of NOP instructions can be processed per second. To make the NOP throughput comparable among processors of different microarchitectures, an architecture-specific factor is used, which for “Raphael” is 2.5x. By comparing the NOP throughput of a Ryzen 9 7950X processor tested with AGESA 220.127.116.11 to 18.104.22.168 (ASUS ROG Crosshair X670E Extreme BIOS versions 0611 vs. 0705); SkatterBencher was able to confirm that that the boost limiter is back in place, and limits Precision Boost frequency to 5.50 GHz when the NopBench load exceeds 4 cores.