You also might want to check to see if you are getting any signal out from the the DVI port on your graphics card. If you have a DVI to S/VGA adapter
plug it into the DVI port and use your Serial cable to connect between the monitor and graphics card.
I had a similar situation only I wasn't getting any picture I thought that my computer was taking a dive and for some reason I changed DVI cables and my picture came back. Suggestion: check with a different DVI cable before you try anything more drastic.