No EDID info from a monitor? Try replacing the cable.

After some upgrades (kernel and otherwise) to an Ubuntu 12 workstation, a user reported one of their monitors insisted on displaying at low resolution (800x600, instead of the 1920x1024 it had previously). I eventually figured out that X and/or the driver (both Radeon and proprietary ATI) could not get EDID info from the monitor anymore. This lead down a few rabbit holes, including a bug in Intel's driver and reflashing EDID info on the affected monitor.

In the end, though? Replacing the goram cable (analog, if that makes a difference) did the trick. I now have the cable, cut in half, hanging over my desk as a trophy.