With Steam just going open beta recently and it being a few years since I last tried a linux distribution on my desktop PC, I decided it was time to install 12.04 and see how things had changed. Everything was going smoothly until it came time to work on my monitor setup.
I have 2 different ATI cards, a 5400 for my two side monitors, and a 7850 for my middle primary monitor and a TV connected via HDMI that is on occasionally for XBMC. Everytime I've tried to move to Ubuntu getting a multi monitor set up running has always brought me to a halt. The amount of misinformation and dispersity on topics like the xorg.conf config file, RandR, Xinerama, compositioning, hardware acceleration, driver support, compiz and Unity capabilities is staggering.
Once installed, the most recent proprietary drivers from ATI detected all of my monitors and let me get them side to side in the proper configuration with no issue. Looking good, however enabling the multi monitor set up without Xinerama just made the other monitors completely unusable showing nothing but a blank desktop. The Xinerama option was available in the drivers menu and I was able to get it working well between my 3 monitors in KDE and Gnome2 (hotswapping the TV caused issues with the setup, Unity and Compiz are completely broken with Xinerama enabled) but then I found out that Xinerama was an outdated solution that disabled compositioning and hardware acceleration. So using the primary monitor for gaming wasn't an option.
Then by chance I stumbled across RandR, on the proposed list of features on the Wikipedia article for RandR there is mentioned support for multiple GPUs in version 1.5. The only information I gathered on RandR was that finding information about it is difficult and that Phoronix had some tech demonstrations articles posted 6 months ago. So that's a no go as well.
So what options are there and who's responsibility is it to incorporate multiple monitors on multiple gpus support with hardware acceleration and compositioning? ATI and Nvidias? Or Xorgs RandR? For a feature that is so easily enabled in Windows and the vendor drivers, it's very lacking in linux.