Re: failing PSU?
Do this, take out your PSU plug in have the power turned off. Take out a paper clip, stick one end in the green wire, the other in the black turn it on. If it doesn't work try a different combination you gotta find the switch. (On the MOBO power this is)
Or do a barebone bootup.
I've seen countless times poeple go "PSU fried" when in fact it was somthing else, it could be a lighting strike hit your internet box, traveled through the cable and into the MOBO or NIC card frying it.
Its going be trail and error.
Normally PSUs either blow up, or die out slowly.
Main Rig: I7 920 CPU, 6 Gigs ram 5870 GPU
M17X Laptop 2.8 Ghz Dual Core, 4870 Radeon