[Stammer]

It could be anything. When I was building a computer, I tried to turn it on and it stayed on for a few seconds and just shut off. Turned out being the processor wasn't getting cooled properly and would just shut itself down.

However I doubt it's the same case with your computer since you can still use your computer. I'd say ya it's probally the PS, but to make sure swamp it out with and extra if you have one lying around.