Nvidia Geforce 680 GTX - Glitches on screen

Check on Nvidia's Unix Driver Archive or Driver Downloads which version of their drivers support your card (GeForce GTX 680). In this case it's 304.1170 and 331.20.

Check on packages.ubuntu.com if this package is provided for 12.04. If not, then check for it in the proposed repo (see how to search for proposed updates on ubuntu.com and BinaryDriverHowto/Nvidia). Both versions are packaged for Precise in updates or proposed repositories: “nvidia-graphics-drivers-304-updates” and “nvidia-graphics-drivers-331-updates”.

You can enable updates repo in Synaptic > Settings > Repos > Updates > Updates and then install the latest nvidia-304 (actually 304.116 is available). You can use Additional Drivers to enable this driver. Prior to doing so, you may want to sudo apt-get remove --purge nvidia-304.

If that doesn't work, you can enable proposed repo in Synaptic > Settings > Repos > Updates > Proposed and then install the latest nvidia-331. You can use Additional Drivers to enable this driver.

After installing the necessary driver, sometimes it's necessary to run sudo nvidia-xconfig. See NVIDIA X Server Settings lost on every reboot.

Reboot.