So your PC only has DVi outputs? If that is the case, then you only have an external video source, and it sounds like it got fried! Take out the video card and see if your PC offers a beep. If it does, then the video card is fried! If it doesnt beep, then the problem is with the MB, as it does not detect there is no video source. Post back!
I encourage you to hook the PC up to another display, not the other way around.
It's kind of fun to do the impossible! -Walter Elias Disney