I'M NOT SURE IF IT IS THE POWER SUPPLY ( 450 W) OR THE CPU IS OVERHEATING? THERE IS DAYS I LEAVE MY COMPUTER ON AND NOTHING HAPPENS, SOME OTHER DAYS I TURN IT ON WORK ON SOMETHING AND IT SHUTSDOWN BUT THE LIGHT IN DA FRONT IS ON, FANS AND EVERYTHING ELSE IS DOWN. IN ORDER TO TURN IT BACK ON I HAVE FLIP THE MAIN SWITCH IN DA BACK, "OFF" TO TURN IT BACK ON I HAVE TO WAIT A FEW MINUTES OTHER WISE IT WILL TURN ON AND SHUTDOWN AGAIN. PLEASE SOMEONE HELP ME!
Try waiting for a few minutes and then restarting without turning your PS switch off. if this works then I would say that you CPU is overheating. if this doesn't work then I would say that you PS is having some problems as the ON/OFF switch will reset the internal breaker. if you a ton of stuff on your PC you may be pulling to much of a load. most of the PS are switching supplies which means that it will overheat itself trying to supply enough current to run you computer. Try blowing and vacuuming your PC and supply out (carefully).