[deafguy]

Hi, most likely it's the power supply. A few years ago there were a lot of threads regarding this issue, try a search.
You could track down a new PS, but I'd recommend taking a stab at fixing it yourself.
If it's the 'same' problem, it's as simple as reheating the solder joints on the PS at the main connector. I don't know why, but for some reason those joints develop cracks over time.
Anyway, it'll take you longer to get access to the PS than it will to find and fix the cracks.

good luck