Comment 7 for bug 1078695

I don't know if it is relevant here, but I got the same response from xrandr (about gamma), and also struggled with wrong resolutions. For me, the cause was the 'nomodeset' kernel parameter, this (i.e. disabling kernel modesetting) caused the i915 graphics driver to fail, and the vesa driver to be used instead. Perhaps you can check in /var/log/Xorg.0.log that the correct driver is being used? The log also contains the kernel command linke - although you may have to use 'nomodeset' to get nvidia to work (that was the reason it was in mine - when I removed the graphics card, I forgot to revert the grub options).