Is the crapped up PSU a foxlink brand powersupply?
If so, then It follows a trend of a bunch of people's psu's doing this same thing.
I had one do it. It eventaully just crapped out. Check the back prongs to see if they looks burnt or scared as if by electrical shock. If they do look like that, It may help prove that the Foxlink brand PSUs use prongs that are hollow and inferior as apposed to the delta prongs that are solid.
If its not a foxlink psu Im stumped but if it is make sure to find a delta brand power supply when you buy a replacement.