Ubuntu – Nvidia-prime extended desktop stopped working


Dell XPS 14z; up-to-date Trusty, nVidia 520m (I think), display port wired to nVidia card.

I had nvidia-prime running on Trusty all fine, with an extended desktop to an external monitor via the display port.

In December, some updates were installed and following a restart, I am unable to get an extended desktop to work. I have been waiting in case a fresher update fixes this, but no such luck so far.

When enabled as an extended desktop, it appears that the two monitors are somewhat overlayed on each other, but the image on the screens appears stretched too. Certain areas of the screen, mouse clicking is offset somewhat too.

Attached are a photo of the 'corrupted' display, a screenshot of the display when corrupted (though this actually looks reasonable) and a screenshot of the updates that were installed in December, to cause the issue.

Any idea what has caused the fault or how I can fix it?


Photo of corrupted desktop
Screenshot, mostly OK
Updated Package

Best Answer

The compiz fix suggested here solved the problem for me.

Francisco Gouveia (fgouveia87) wrote on 2015-03-10:

After days lost with replacing NVidia drivers and manually editing xorg.conf file, I finally found this!

Rockwalrus (rockwalrus) solution works!

On CompizConfig Settings Manager, go to "General Options", then "Display Settings" and do the following:

  • Uncheck "Deteck Outputs"
  • In the Outputs array, set the resolutions of each of your screens. The numbers after the resolution "1920x1080+0+0" are the offset. It's important to add this offset according to your needs. I have two full HD screens, so I added the following configuration: 1920x1080+0+0 1920x1080+1920+0

The second output has an offset of 1920, because it is on the right side of the first output, which has a width of 1920.

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