Weird new build problems


Dec 13, 2012
Hi, I reccently built a new computer with the following specifications:

NZXT Guardian 921RB case
Intel Core i5 3570 CPU
Corsair Vengeance CMZ8GX3M2A1600C9B 8GB (2x4GB) DDR3 RAM
nvidia gtx 460 glh GPU
ASUS P8B75-M Motherboard
Corsair GS-600 V2 Power Supply
Seagate 320 GB HDD

So when i first loaded the new system it worked for a day and then the old PSU died, which i half expected because it was 550W of a cheap brand. I replaced it with this new one and when i rigged it up the computer worked but i would get random freezes after short amounts of time and then it would reset itself, i then thought it was a software issue so i installed windows 7 and the problem had seemed to disappear. After a short while the screen started to turns off and then on every so often and since i am using it on a tv i thought not much of it, it wasn't until the display started dying and the computer started to reset itself that realised something was wrong, when i turn on the computer it will sometimes make it to the BIOS, it will sometimes freeze in the BIOS, sometimes it will not make it to the motherboard screen, sometimes it will make it to the windows logo. I am not sure what to make of this since i made sure the PSU would be enough for this system. I can confirm its not overheating because i have checked the temps in the BIOS and nothing seems to be running at high loads.
Any ideas or help as to why the computer wont load would be greatly appreciated.