Can't POST, GA-M57SLI-S4

[shadowrun]

I put this rig together a little over a year ago and it's been fine with a few problems here and there. A couple of months ago it would shut off or reboot on it's own. Now it doesn't POST, illuminate the keyboard or mouse at all. Last month I had it working for a moment until i plugged in my ethernet cable and at that moment it decided to shut off never to boot again.
ALL of the fans are working fine, the Hard drives are spinning, the DVD drive has power.
All of the peripherals are getting power ( a DVD drive, 2 hard drives, 2 evga 8600gt's sli spin their fans fine ). But I get no display or usb power..no post at all. I'm hoping my power supply had a brownout and i only need a new one (turbolink atx-cw500p4 500w)
I reseated my 2 ram sticks (1gb each), reconnected all power cables, idunnowtfxup?

Someone has gotta have this motherboard!

 

[The Brick]

Sounds like something crapped out. If you have other computers around you, try swapping components (start with PSU and mainboard+cpu).

 

[Krynn72]

Sounds like either your PSU is bummed, or your PSU bummed your motherboard. 500 watts isnt much for 3 disk drives, a dual/quad core processor and SLI-ed video cards. You've probably been pushing that thing pretty hard.

 

[Asus]

Have you unplugged the ATX power plug to the motherboard and looked at the end of the plug for burn marks or on your motherboard where it plugs in?
Just check simple stuff that the mobo might need before/after POST like CPU fan plugged into the board or jumpers in correct spot (if you messed with them before) or IDE/SATA cable is plugged in secure. etc

 

[shadowrun]

I got my machine up and running today. The problem was the power supply, i'm so glad it wasn't the motherboard. I upgraded from a 450w to a 750w corsair. the 450w was so loud and whiny, this one doesn't make any sound at all even with a giant fan to cool it. Thanks for the help gamers