I’m using an ASRock Taichi X399. Updating the bios to the latest (still beta) bios fixed the issue.
Now everything is running perfectly @4100Mhz@1.325V.
BIOS 2.0: suffers from windows sleep bug when overclocking
BIOS 1.91E (beta): fixes windows sleep bug, but has unstable bus clock while overclocking
I raised a ticket at Asrock hoping they fix the issue.
@wendell any chance you can check with your contacts at Asrock if they are aware that both BIOS 2.0 and BIOS 1.91E (beta) suffer from issues when overclocking? As a result I can only conclude that at this moment overclocking ThreadRipper on a Asrock Taichi X399 is not functional.
Flashed again BIOS 1.91E, did a simple overclock to 3.8Ghz @1.325V. Fixed APU/PCIe frequency to 100Mhz (so 38x multiplier).
Uninstalled AMD Ryzen Master, disabled c-states, disabled Core Performance Boost … and still the frequency is jumping up and down in CPUID HWMonitor. It’s harder to notice in HWiNFO64.
This doesn’t happen with BIOS 2.0 … but then you have the windows sleep bug
@wendell my issues with overclocking my threadripper are finally fixed.
Asrock help desk has been very helpful and provided different early BIOS releases. Now happily running BIOS version 2.35.
Very reassuring that Asrock help desk actually listens and helps their customers!