Power unresponsive unless PSU power button is flipped

[PvtRichardson]

I'm away from my computer just now and can't check the cause but I was hoping someone might have some experience or ideas on the matter.

The power button on my case is completely unresponsive unless the PSU power button is flipped, sometimes it takes just one on and off motion sometimes it takes several, I've checked all the connection on the case power button and nothing is wrong there, I'm assuming its a PSU problem but i've only owned the thing for about 4 or 5 months. Any help appreciated thanks.

[EndlessWaves]

Usually you only have to flip the PSU power button to reset the PSU's safeties so I'd go over the system, take the motherboard out etc. and ensure nothing's shorting out.