I have two graphics cards -- ATI Radeon HD 4770 and the built-in ATI Radeon HD 4200 -- which I run on Ubuntu 11.10 x64.

Up until now I have had the 4200 disabled and just have been using both displays on the 4770. I thought I would try putting one display on each card (after all, aren't two cards better than 1?).

I am having a bit of trouble, so I was hoping someone could enlighten me on what is the best way to go about doing this.

I am currently using them both successfully with Xinerama. There seem to be no ill effects, except that Xinerama and xrandr don't really play nicely, and there is no compositing with Xinerama. Not a big deal, but it does make the desktop less beautiful.

What I wanted to do was to set it up without Xinerama, and just use the two displays as individual screens. However, this turned out to be buggy... the mouse was able to move between screens just fine, but I wasn't able to do anything on the second screen. It was all white, and the wallpaper was sometimes visible and other times not visible, and I was unable to open any programs on the 2nd screen. At one point I was able to right click and make a new file on the 2nd screen desktop, then open it with gedit, however this caused some strange behavior on the first screen's desktop.

So, any advice? Is it impossible to have 2 separate screens without using Xinerama? Or am I doing it all wrong by assuming it's better to use both cards instead of disabling one of them and putting both displays on the other one.

Any advice would be greatly appreciated!!