On a Dell XPS 15, running Ubuntu 14.04, the HDMI and Displayport ports work fine, but when I plug in two screens to both the DP and HDMI, it doesn't work.
The screens window showed some error dialogs about bad configuration:

Could not switch the monitor configuration:
could not set the configuration for CRTC 64
Failed to apply configuration: %s
GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._gnome_2drr_2derror_2dquark.Code2: could not set the configuration for CRTC 64

When I force the second external screen "on" and click apply, the screens go all black except for a non-responsive cursor.

I tried with the Nvidia driver app in Nvidia (Performance mode), or Intel (Power Saving Mode). (after restarting). It still doesn't allow 2 external screens.

Update: it doesn't work under Windows with 3 displays either.

  • 1
    Are you sure your laptop hardware is capable of triple display? Most nVidia cards can only do two simultaneous displays. What is the model number of the laptop? If you turn off the laptop screen, can you then turn on both the external monitors at the same time?
    – bain
    Jul 29, 2014 at 1:01
  • >> 1. Do two monitors work without any error? >> 2. Does the triple monitor configuration work on nouveau? >> 3. Is your computer operational when you have all 3 monitors hooked up, how does it act in this situation exactly? >> 4. What does your xorg.conf file contain? -- I had quite the adventure with my video setup since upgrading to 14.04, even encountered that exact error you have, so if you come back with more info maybe we can work something out.
    – iffy
    Aug 1, 2014 at 8:16

1 Answer 1


If These 2 external screens are in addition to the internal screen, the problem is probably that your graphics card only supports a total of 2 monitors and ubuntu is not telling you. If you would like to use 2 external monitors, first disable your internal laptop screen.

Edit: A few years later, another solution appears: There are now DisplayLink drivers for Ubuntu! If you get a usb to [vga/hdmi/whatever] converter, you can plug one of your external monitors in to it and run a total of 3 displays: one off of usb.

  • I think this may be the case, I tried under Windows and it doesn't allow 3 screens working either. :(
    – NoBugs
    Jul 29, 2014 at 1:20
  • 1
    Yes, then that is the case. I had the same problem with my old laptop. Windows will tell me that it only supports 2 displays but ubuntu will happily glitch all of them. Sorry about that. Please mark my question as the answer if it solves your problem.
    – Blaine
    Jul 29, 2014 at 2:08

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