Make external display work (discrete videocard)
I've installed Ubuntu, and external display was not recognized by xrandr, although it showed Ubuntu logo while it was loading.
I've tried to install drivers for NVidia (Bumblebee -- no changes, and those proprietary from NVidia website -- they broke something in my Ubuntu 12.10 window manage, so that it loaded without window borders, taskbar, nothing, so I reinstalled OS).
All what I actually needed is to just change BIOS setting to "Discrete Videocard". And voi-la, external monitor works smoothly! I haven't installed anything extra, just Ubuntu 12.04 out-of-the-box.
It would be useful to add patch to Ubuntu default nvidia drivers that would use discrete videocard if external monitor plugged in.
My setup was: At first Ubuntu 12.10, after reinstall it's Ubuntu 12.04. Lenovo ThinkPad W530, NVidia K1000M (Optimus).