NVIDiA GeForce 8600GT
your nvidia card sounds trashed, there are a few things you can do to fix it, sometimes it works sometimes not, you can use mineral terpentine to wash it, it might have some dust lodged in it, or (no kidding) wash with water (added advantage of squirting it hard) leave to bake in the hot sun for hours and hours (depends where you are on the earth, helps with hot concrete).
one suggestion i heard (but have not done yet) is put one card in, save the Xorg conf, remove, put the next card in its slot and save the Xorg conf then merge them. nowadays it may (SUSE does, not sure about Ubuntu) work without an Xorg.conf and you gotta get it to make an Xorg.conf for you (which you will have to do twice, and move both files out of that directory), having none there makes it decide for itself.
edit: if you use "LeftOf" when you are arrange the screens you may encounter a problem with the mouse - if you do you have to place your start up screen (zero) at 0,0 and all the screens to the right of it. i am not sure if there is problems with putting a screen above.... (maybe i wasnt supposed to enter negative coordinates when placing the left side screen, who knows, i gave up and removed linux)
Last edited by charlieb000; 02-26-2011 at 04:39 PM.