Recently there has been much talk about RandR 1.2 support with
RadeonHD and Nouveau (among other drivers), and as a result we have been
asked many times now "what is RandR, and why do I care?" Well, RandR is
the "Resize and Rotate" extension in X.Org and the v1.2 update
introduces new functionality such as dynamic hot-plugging support for
display devices. To help those who may be new to Linux or just never
took advantage of this X.Org technology, we have written a brief guide
with some of the RandR basics.
Recommended: Click here to Update all your outdated drivers