Have a 2008 Mac Pro, Model 3,1. Came with the Nvidia 8800GT 512mb PCIe graphics card. I think the card is going bad. When I try to load up a game, the machine freezes. On reboot I see the typical green stripes/lines, as well as artifacts. If I let the card cool it works fine in OS X. But anything graphic intensive causes a crash. Sounds like the video card, right? Assuming it is the card, what are my options? Can I put the Nvdia GT 120 card in this 2008 3,1 Mac Pro? Is the GT 120 as good, or better, than the 8800 GT? Or should I just get another 8800 GT? Any other cards I should look at? Finally, is it an easy replacement? Do the replacement cards for Mac Pros come with driver software? Asking because I've never done a video card upgrade on a Mac, only PC. Annoyed my 8800 GT is failing, but I'm not under warranty, so any input is appreciated.