I built a pc about 2 years ago. It is a custom loop water cooled i5 2500k, a sapphire hd 7870 ghz edition, 2x4gb intel extreme masters ram, wd 1tb hdd, rosewill bronze 1000w psu. Since probably a year ago it has been black screen crashing. The computer will not physically crash itself, all the fans will keep running at full speed from the sounds of it and i can normally still talk on skype and i still have sound to the game i was still playing. The crashes are sporadic. The screen will just randomly turn black and i will not be able to do anything and will be forced to reset the computer. I have tried everything i could think of: first i disabled my overclock (although it was running at safe voltages and temperatures i figured i would give it a shot), i disabled the boost clock on my gpu, i tried to down clock my gpu, i have ran just about every stress test i can think of and it still runs fine (it will only crash while gaming), ran windows memory diagnostic, even a system restore. The only thing i could still do but havent bothered to is put fresh thermal paste on the processor. Other than that, i do not have extra parts laying around to sub in 1 part at a time until the problem is resolved. Please help.