I had the same problem, with displayconfig-gtk running under bullet-
proof-x and trying to switch from vesa to nv. Only 640x480 and 800x600
were offered.
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Displayconfig does not detect the screen resolution
https://bugs.launchpad.net/bugs/150467
You received this bug notification because you a
I confirm this bug. Sometimes, displayconfig want to use the VESA driver
only and display only VESA available mode. Another possible cause is
that sometimes displayconfig force refresh rates that are not compatible
with the native screen resolution. You have to remove it manually from
the xorg.conf
