gigabyte MB won't even give beep codes, even after the RAM and CPU was removed, and we used a known working Video card, and when plugged into the board it constantly cycled through an on/off state, like it was constantly resetting itself.
Make sure you're not grounding out the mobo on the case. You might have a screw to tight and the board is grounding out. or a screw on the case somewhere grounding out... It's rare. But it happens... I'd loosen all the screws and double check all the connections. Then retry. Let us know what you end up doing.