Well. What can I say. I've never had issues with nivida, KDE, Xfce, LCD or CRT, and a variety of motherboards from Slot A to skt-939 to am2, single and dual core athlons, stock Slackware and SLAMD64 that weren't either hardware failure or my own doing.
There is always brute force: backup your data and repartition/full install. Swap nvidia card, swap monitor.