My beloved MacPro took a dump the other night..Before dying the characters on the screen got jumbled and the screen flickered..It will only reboot with the line going about half way then the characters go nuts again and it overall freezes...I believe it has a GeForce 8800 GT, which was replaced by Apple many years ago when still under warranty...Do you think its the video card or motherboard...?? Im (im)patiently waiting to replace it, but nothing yet on the horizon...I'm using a Dell now with Win-10...Gawd I hate it....