Setup: two monitors: Samsung 305t with supported modes of 2560x1600 and 1280x800 and HP2475W with lots of modes ranging up to 1920x1200. HP is physically on the right side and pivoted 90 degs clockwise. GPU is GT7950 with render target limit of 4096x4096.

Starting X without xorg.conf: both monitors are in highest res mode cloned, with the HP showing only part of the screen (clipped at right side and below).

Starting with xorg.conf that instructs the HP (DVI-I-1) to be RightOf the Samsung (DVI-I-2): Graphics ends up in a very unsuable state (see bug 37000). Starting X without xorg.conf and using xrandr to achive the same: Samsung gets blanked, HP is on. xrandr says the screen size is 1920x1200 and that maximum screen size is 4096x4096. As the resolutions of 1920 and 2560 exceed the 4096, this is expected.

Starting with xorg.conf that instructs the HP (DVI-I-1) to be RightOf the Samsung (DVI-I-2) and rotated left: HP is properly rotated and is logically on the right of the Samsung (ie. moving the mouse to right makes it appear to the HP and moving it left moves it to the Samsung), but the Samsung screen is only activated to 1280x800 mode. Activating the higher resolution with xrandr at this point, or starting from the configuration-less cloned mode (first case) and ordering the rotation and alignment with xrandr (no need to force the resolution in this case) corrupts the Samsung image. The corruption makes the applications and background image wrong, but mouse cursor is fine. It even changes from arrow to caret when hovering above a terminal.

Finally trying to set the HP below the Samsung with or without rotation works fine.