If your PSU was cheap, it could very well harm other compnenets in your machine. What brand of power supply did you have?
You will have to swap out your bad supply with a new one. First, use this Antec Power Supply Calculator
to determine what wattage you need. Utilization rate usually does not exceed 75%, use that value instead of the recommended 90%.
Antec, Corsair, Cooler Master, OCZ, XFX, Seasonic and Silverstone are decent manufacturers for a replacement.