EVGA GTX 750ti FTW crashing in my x51

Hi guys,

I just got the EVGA 750ti FTW for my R1 X51.....I cannot get it to work properly. It randomly crashes anywhere from one minute to 3 hours into a game or benchmark. If anyone could give me any help that would be amazing because I am currently driving myself insane!

I have tried all the usual things, cleared all drivers and reinstalled, checked the cables, reseated the card and so far I am not having any joy.