Help needed diagnosing power issue

[s1xtyn1n3]

So my PC just switched off - was pretty much idling, no bsod or anything. At first I thought it might have been a power cut, but when i checked, my monitors and speakers still had power.

So I tried to boot the PC..... nothing.

I then noticed that the wifi usb adapter connected to the motherboard and my internal xbox 360 wireless receiver both had lit LEDs - so i tried again.... nothing.

I am noticing occasionally the briefest of flashes of the case LED but still nothing.

So, my mobo has power as it's powering USB devices which means that it hasn't fused the cable or completely blown the PSU, but I'm getting no sign of life when trying to boot - no beeps, spinning fans or anything.

Any thoughts on what might be wrong?

I can't quite remember the exact model of the PSU but its about 1 year old, Corsair 600W semi-modular.

Just about to check the switch connections to the motherboard. Besides that i'm stumped.

 

[s1xtyn1n3]

Ok, it was the switch - i was looking at the mobo connectors and they all looked ok, but the connector that hooks up to the tiny pcb on the side of the case had come ever so slightly loose.

*phew*