Check your motherboard for "bloated" capacitors. You'll know when the cylinders are disfigured in any way. This is a sign that the mobo's busted. Also, I'd steer clear of the sub-Php1000 power supplies. Go for branded PSUs (Task, Hec, Antec, Coolermaster, etc.). They might cost you 2000 bucks or higher for a 350-watt but the large input/output capacitors and beefier components make sure you get steady power at all times. A branded 350 is likely to last longer than a generic 500.