[SOLVED] Similar symptoms due to bad DVI connection; check plugs
Had a similar problem today on Debian Wheezy, kernel release 3.2.0-4-686-pae, GNOME 3.4.2. In xrandr's output, only resolutions up to 1024x768 were displayed for the monitor connected to 'DVI-0', although its native resolution of 1280x1024 should have been available, too. Before this, it used to work as desired, with the same hardware, though the graphics board recently had been removed and then subsequently reseated into its slot. Apparently, the monitor's EDID wasn't read properly. In the GNOME 'System settings' dialogue 'Displays', the affected monitor showed up with the label "Unknown" rather than a more descriptive (EDID-derived) label. Any combination of rebooting and using 'Detect Displays' failed to change the result.
The problem has been solved by plugging the DVI connector into its port on the graphics board again, so as to insure that it is plugged in fully and properly. Running xrandr directly afterwards has caused all connected monitors to flicker briefly while switching their modes. The DVI-connected monitor has remained properly detected since then, enabling usage of the 1280x1024 resolution. The output of xrandr and the label in the 'Displays' settings dialogue all have returned to the desired state, too.
Note that while the problem persisted, the monitor appeared to work correctly, other than the lack of specific EDID information and thus having to use the lower resolution. That is, there were no apparent erroneous graphics artefacts or glitches. For this reason, it didn't seem obvious that the DVI connection was responsible.
Last edited by t626383; 05-07-2013 at 04:03 PM.