Absolutely No Video on Computer

My X800 XT AIW card overheated, so I tried replacing with an new X800 XT card. Nothing. I then tried another card, an ATI 7500, which gets all of its power from the AGP connection. That didn't work either.

Did the overheating card cause damage to the motherboard?

Thanks for an guidance you can offer.

An overheating video card shouldn't damage any other component really. It's possible you mistook a different problem for video overheating perhaps. Try the original card in a different system if at all possible to confirm that it was the issue to begin with. Honestly it seems like you've confirmed that the video card itself is the one thing that isn't causing the problem. Lack of video can be any of a huge number of problems. As coozie said, could be the monitor, could be that your AGP port died, could be a different problem with the motherboard, could be the PSU, ect.