PC wont work after shutting it self down

[Trijay]

PC died after 8-10 hours of gameplay, Clicking the Power button doesnt do anything. I tried removing the side panel of the case so air would flow inside and cool it . after a while, i tried to power it on but after 5 minutes it died again. i tried to change its Mobo and Processor but it did the same thing the next day. I am thinking about buying a new PSU and upgrade to a Mid Tower Case or is there something more that i should replace? HELP ME PLEASE I CANT ENJOY MY PC WHEN ITS ALWAYS SHUTTING DOWN


Windows 7 64-bit
AMD Phenom II X4
Geforce GTX 460 SE
Gigabyte Mobo
4 GB Ram
500W Voltage PSU

 

[yeticorn]

Please elaborate as to what diagnostic measures you have taken to narrow down the problem.