i7-2600K can't go 4.7

hello everyone

for over 3 mounths i use OC @4,5, manual 1.345, HT off, LLc- ultra high, PLL voltage 1.7, PLL over voltage disable

Specs in my signature

i tried go up to to 4.7 GHz but even in 1.41V i get BSOD 124, at prime 95 blend test after 45-60 miniutes

any idea what can i do ?

thanks