Comment 9 for bug 555641

Kory: Are you on ATI? There is a problem on Intel at least where a single monitor at 2048xwhatever does not work and it was causing a large amount of bug reports where things were unusable and black on first boot because of it, thats why it was changed to >= maxTextureSize (the bug number is in the compiz changelog)

There is work being done to get around this in the future with xrandr 1.4 though as well, but it is some time off. A snippet out of the protocol change:

+1.4 Introduction to version 1.4 of the extension
+
+Version 1.4 adds a couple more capabilities to further expose the
+underlying hardware to clients
+
+ • Per-crtc pixmaps. This provides for multiple scan-out buffers
+ which applications can create and assign to arbitrary collections
+ of crtcs. These pixmaps can be associated with a window for use
+ with OpenGL or drawn to directly.
+
+ • RRSetCrtcConfigs request. This supplies a set of
+ crtc configurations to the server that must be applied together
+ or not at all. This can reduce screen flicker while also
+ providing the server a complete configuration for appropriate
+ resource management.
+