computer screen goes black at windows start up screen and restarts

[Knightofgale]

my problem is really annoying and i have been searching for a cure for a while without any results. the issue is, 50% of the time when it reaches the windows start up screen the monitor will go black and the fans will begin to spin at full power then the computer will restart. however, the other half of the time the system will load just fine but randomly the same black screen and restart will happen. however, when the monitor is hooked up to the on board graphics card the computer works just fine. at first i thought it was a graphics card problem so i rmaed my graphics card. when i revived the new card the issue still persisted. then i tried changing which pci e slot it was in and that didn't help. i then ran a memtest and that showed no errors. finally i started the system in safe mode and it still produced the issue. so now i am at a loss any help would be greatly appreciated.

system specs:

ASRock Z77 Extreme4
Corsair HX Series HX850 850W Pcu
Intel Core i7-3770K
8gb Corsair Vengeance ram
MSI GeForce GTX 560 Ti

 

[Knightofgale]

oh i also checked the temps and they never went above 60 and i tried different drivers and also reformatted and did a clean install of windows