It looks like you may have a dead video card, if you don't get any signal when you try to use it. It's possible your power supply can't supply enough power to turn the card on. Without actually being there in front of your system, its kind of hard to tell whats going on. Is there a setting in the bios to disable onboard video? Can't remember if its been asked before and what motherboard are you using or what system did you buy?
