hi a few weeks ago my computer was crashing continuously. i downloaded speed fan and found out that my graphics card was running at around 100degrees. so i turned the fans up to 100% so after that it was at around 40 degrees while i monitored it regularly. my computer continued to crash regularly. so i bought water cooling for my cpu. now it only crashes while i play games. (the only game i play is diablo 3.) i reformatted the computer and its still crashing. sometimes a black screen with grey vertical stripes, sometimes just a black screen and sometimes just a blue screen. never any writing. also the screen changes to those colours and the computer keeps running for about 10 seconds then beeps and turns off.

specs if i remember.

intel i5 2500+
gigabyte z68x-ud3h-b3
Gigabyte ATI HD7970 OC Edition 3G
corsair vengeance ddr3 16gb (Cant remember the specifics
(i dont think the rest matters.
is there any way for me to be sure what is going wrong?
sorry im not very good at this and i dont want to keep replacing things that arent the problem
thanks