I'm getting problems with my PC just spontaneously rebooting when running linpack with 1.45vcore or more. Tested at 400x9, which is linpack stable at 1.344v, if i increase voltage to more than 1.44v PC will reboot after a couple of minutes of linpack I previously thought it was my PSU not providing a clean enough current, but after buying one for £95 (corsair TX750W), it still does it. Does this sound like my VRM's are overheating? Any help or advice will be appreciated.

EDIT: oh and it's not CPU temps, max i got during linpack was 78c which isn't enough to make my pc reboot.