PC will not boot, no fans, no lights, nothing..

My set up goes as follows:

ASUS P5N-E SLI
Intel Core 2 duo processor
2x DDR2 2GB PC6400
Corsair GS600
EVGA 8800 GTX


With this setup my PC worked great for a good 2-3 years, one night i left it on and the next morning it was off. The green light toward the bottom right corner of the mother board is on and steady green, but nothing happens when I push the power bottom on the case. No other lights, no fans, no beeps, nothing. Ive tried getting a new power supply and changing that but just ended with the same symptoms. There are no strange smells or marks or anything coming from that box. Please help!