I5 7600k acting weird when overclocked

[EquaLiZr]

I'm using prime 95 to stress my cpu at 4.8ghz (which seems to be the sweet spot for most) but when prime is running my cpu downclocks itself to 4.5ghz quite often (i'm using HWmonitor) Temps are fine maxing out at 67c air cooled and volts are at 1.291v

Why is the cpu doing this?

 

[Ocellaris]

Sounds like AVX Offset kicking in. Check for the setting in your BIOS.

 

[EquaLiZr]

I have it set to zero. Same thing

 

[Araxie]

You are reaching the power limit. you have to enter in BIOS and increase said value..

 

[Frito11]

motherboard vrm throttling perhaps? check current settings in bios. also make sure windows is set to performance mode. barring all that if it always goes down -2 on an avx load i'd say the mobo is forcing an avx offset on you and lying.