……Regarding your earlier comment, the Clock Speed will vary if CPU IEST is enabled as the CPU multiplier changes.
Mine varies with it disabled so perhaps the other settings in 'Advanced BIOS Features' play a part
Is my CPU behaving correctly? In CPU-Z the multiplyer and clock speed keeps changing?
If CPU IEST is enabled it is designed to reduce the multiplier and therefore your speed at ‘quiet’ times.
Generally a good idea perhaps but not normally recommended when testing overclocking.