PC is down

[Enzothedog]

Can any one help...
My computer will not boot up. I can't even get to the BIOS. It just shut down last night and now I cant restart it. It does try to restart every now and then by it's self. I have an Asus a8n-e I have tried two different processors (AMD 3700 and OPTY 175) Repalced ram Still nothing. I have a green LED that is on the mother board...it is on. My power supply is an Antec Neo he-500 and a EVGA 7900gt video card.
Mother Board?
Power Supply?
7900GT?
Thanks for any help
Kory

 

[tommytran]

Try to boot it with the least component install (CPU, RAM, Video card if it doesn't have onboard on)

 

[crossrode]

Remove the RAM and boot the computer. If you hear NO beeps, the motherboard does not recognize there is NO RAM in the system. You have a bad MB.

 

[meltdown75]

Another suggestion: reset the CMOS memory.

Barebones is also the way to go when troubleshooting as tommytran suggested.