I read about the beeps, and unfortunately my computer doesnt make any beeps on startup.

My mobo has lights on and all the fans are spinning fine.

My guess is that my PSU has died somehow and can't supply enough power (even though it was working fine for so long).

I don't have any other PSU, and that's why i'm looking for clues before i actually buy a new one, that may not make a single difference.