Try taking the board outside the case, for ruling out a short. Connect both 24 and 8 pin power cables to it. Make sure that they are properly connected. Start the board and see if still no go.
It is a short, took it out and isolated the Mobo on cardboard, it fired right up, I also believe I found what it was.
I had someone else helping me when I installed the Mobo, and the isolating rubber stops weren't on the screws. I didn't even give it a second thought that it might have been those.