Corsair PSU’s are really nice , id upgrade with one of those if i were you
I had the same problems due to graphic card overheating, so check that.
OK guys, I finally purchased a new power supply [Corsair 650w PS from Bestbuy, $99.00] and my system is running flawlessly!!! It’s amazing, like a new baby. It even feels faster. It runs quieter (I guess all the noise was coming from the PS fans). I guess the CPU and hard drive run faster if they have strong consistant power running through them. I love my system again.