The first I would do is pull out the XFX GEFORCE 6800 PCI-E 128MB DUAL DVI card, and throw in a old PCI card in to your PCI slot and see is it power up if it does it could be powersupply or video card is bad. If it doesn't you motherboard is Bad. (FROM THE SOULD OF IT YOU FRY THE MOTHERBOARD WHICH WHY YOUR LIGHT COME ON BUT NO FAN NOT A GOOD SIGN, SEEN THIS A FEW TIME CARD PROABLY WASN'T IN ALL THE WAY OR USE A 350 W POWERSUPPLY INSTEAD OF A TRUE POWER 480W OR HIGHER COULD HAVE DONE IT. YOUR COMPUTER TRY PULLING MORE POWER THEN IT COULD CAUSE THE VOLTAGE TO DROP AND THE AMPAGE TO JUMP WHICH WOULD CAUSE DAMAGE TO THE MOTHERBOARD.
1. Athlon 64 3500 89W
2.XFX GEFORCE 6800 PCI-E 128MB DUAL DVI between 77.5 Watts, and 123.5 Watts
3.A8N-SLI Deluxe Motherboard 75W
4.Seagate Barracuda ST3200822AS 200Gb
Power Management (watts)
Seek: 13.5
Read/Write: 13
Idle: 9
Standby: 2
5. DVD drive 12.5 w each
6.Corsair (TWINX1024-3200C2PT) 1024MB 10w
Total is between 302-336
Remeber a 350w not true power can only put out 275w or less. So I say go with a 480w Antec true power or higher.