I've never had a whole lot of success with running more than two screens on X. I say that on a system with three heads and on which I've run up to four for a laugh, but I'm not that happy with it so looking for advice. I have two nVidia cards, for a total of four outputs. I have these configured in xorg.conf using Xinerama. Although GLX loads and appears to work, I'm missing XRANDR and COMPOSITE extensions as these aren't compatible with Xinerama. This really limits me in the window managers I can run.. Gnome 3 shell, Unity and Cinnamon all die horribly, Compiz is impossible to get going, and many others just don't "get" multi-head. XFCE seems to work fine, which is what I've been using for a while, but I really miss having all the niceties of Compiz and Cinnamon. What setup do you use 3+ monitor multi-head on Linux? Cheers, Toby