I have the older G5's and this happen at about 2 years old. I have to look about the name of the cards but its the orginal ones that came with the G5's. I am not sure what killed the cards but I know they were the source of my problem. I am concerned for the long term if I keep having video cards die if I will be able to find replacements.

Thanks for the info about the heat being a possible problem.

Mical