If you are on Linux, there are long time known problems with low power cpu states. These states can be entered by your CPU when under low/no load.

A common approach is to go into the BIOS/UEFI settings and check that c6 is disabled. To verify and/or temporarily turn c6 off, see https://github.com/r4m0n/ZenStates-Linux

It’s also worth checking all the autodetected stuff that can be overclocked, like ram speed. That stuff can be wrong, and then you get crazy but similar bugs in linux and windows.