One more bit of advice before I jump into bed...
If all else fails and nothing I or anyone else posts works... take the board out of the case and place it on a NON-CONDUCTIVE surface like wood or something else.
With the cpu/fan and ram plugged into the board make only the connection for the power switch and the actual power supply to the board. Be careful with the monitor cable connection to the video card as it might try to pull the video card out of the board... with power on this would be VERY BAD! Just make sure it does not. Hook up the keyboard and that's it.... hit the power switch on the front of the case.
You will of course have the case lying next to the removed board for this to take place.
The test here will tell you if the board is grounding out someplace in the case that you can't see.
If it powers up into the bios then you have your answer...
