I've been seeing my Xeon 12‑core dropping from 3.5 GHz to 1.8 GHz randomly during stress tests. BIOS is up‑to‑date, and I've disabled Intel SpeedStep. Any ideas?
Thread #104 – Intermittent CPU Throttling on 12‑Core Xeon
Check the VRM temperatures in your motherboard BIOS. Overheating VRMs often cause throttling even if the CPU itself stays cool. Also, make sure the power plan is set to “High performance.”
I had the same issue on a similar board. Updating the chipset firmware solved it. The OEM had a known bug with C‑states on that SKU.