This is really late.. but the 'no signal' could indicate that your computer hung up in the POST test. Since you recently changed the video cable, I would suggest opening up the box, removing the video card and reinstalling it. It may have shifted when you plugged the cable into it. The traces (pins) on the AGP card are very small, and can easily short to the next pin if the card is not securely installed. Also, other cards (usually the modem card) can fail and cause the system to not boot. Remove all cards except the video card to test this. If it works, then power down, and reinstall one card at a time test booting as you go to discover which card is bad. Since your POST test stopped on the video card, I would bet that the first paragraph would have solved your problem.