without any changes or anything like power outage brown out etc, BEFORE it stopped working (as far as we know nothing like that happened, or he/she would have posted it), its the computer.
how can the pc draw more power than before, especially when nothing changed.
circuit breakers are either closed or open, and gets triggered in the same second you push the power button and nothing would (try) to power on, if the leds turn on/pc tries to power up, it is closed and power on the outlet, and we can exclude it 100%.
the post clearly says the pc won't power on, so why ask if it stays on?
how are you going to verify a psu is good/bad?
do you have the equipment?
i doubt the poster has, or we wouldn't see that question in the first place.
and again, no need to change the outlet. if anything on the pc "lights up", there is power on the outlet, and using another one will make no difference.