Hi , Homebuilt system worked ok for brief while appr. a year ago- Was able to load apps then. not used since. Turned it on today and it worked for a few minutes and shut off. Tried using with only keyboard & mouse - same problem. Will boot up long enough to load win 7 and see apps but soon shuts off. Variable lengths of time ( a few minutes to 7 minutes) before shutting off. Fan at back works, cpu fan and graphic card fans all working. Seems like a hardware problem. All new stuff. Someone mentioned that it could be a bad heat sink - haven't tried new paste yet. Win 7 unlimited, not much on Hard Drive. MB: Gigabyte GA-MA780G-UD3h with AMD athelon 64x2 5000 chip 4 mg ram on 2 chips Corsair DDR2 Nvida GeForce 7600 cgraphic card 550 watt PSU Any help appreciated.