Assuming no beep codes:
Verify heatsink is installed properly. Verify cooling fan is plugged into the proper header (should be labeled "CPU"). Retest.
Still no luck, unplug everything from power supply except for mobo(24pin and 4pin)/videocard connectors. The idea is to plug in only the connections you need to get a boot/BIOS screen. Retest. Try to boot with only one stick of RAM installed, swap sticks.
Still no luck, remove motherboard from case, examine standoffs to see if there are extras, or misplaced standoffs shorting the board. Lay out motherboard on an insulated surface (a piece of cardboard works fine). With only memory and videocard installed. Plug in power supply, momentarily short the "PWR" terminals on the MOBO header where the switch was hooked to. Hopefully it will work.
Edited by dpunisher, 10 December 2008 - 04:26 PM.
I am a retired Ford tech. Next to Fords, any computer is a piece of cake. (The cake, its not a lie)
3770K @4.5, Corsair H100, GTX780, 16gig Samsung, Obsidian 700 (yes there is a 700)