I am using Ubuntu 13.10 on a macbook pro. Would like to install external monitor VGA with the mini-port. no success.

  • Trying: Settings→displays - nothing recognised.
  • Trying xrandr --auto - nothing
  • There is no xorg.conf on my Ubuntu.

In use 2 graphic drivers:

VGA compatible controller Intel Corporation 3rd Gen Core
VGA compatible controller NVIDIA Corporation GK107M

and, OpenGL vendor string: nouveau

What should I do to activate the external monitor (need for beamer presentations)?

2 Answers 2


Reinstall the driver:

sudo apt-get --purge autoremove xserver-xorg-video-nouveau && sudo apt-get install xserver-xorg-video-nouveau

If the problem still exists, run :

sudo dpkg-reconfigure -phigh xserver-xorg

This is what helped me:

  • Identify the external port. In my machine this is DP-1. xrandr lists them, but they have slightly different names for the kernel. For instance, xrandr calls DP1 what the kernel calls DP-1.

  • Boot the machine with the port enabled, by passing the parameter video=<port>:<res>e. The e means "force output to be enabled, even if it looks like there's nothing on the other end". For instance, I have to add: video=DP-1:1024x768e

To boot the kernel passing a parameter: enter the grub menu at boot (press Shift if the menu is skipped), press e on the first menu entry (default, latest kernel), go to the line that begins with linux /vmlinuz or something similar, and add your choice of video=<port>:<res>e to the end of that line. Then press Ctrl-X to boot.

The resolution, as far as I know, is mostly irrelevant, although the ratio seems to be. xrandr/Ubuntu will later let you play with it a little and change it.

When you boot, you should be able to see "a monitor", although it may appear disabled by default. Try to enable it a few times. In my machine, it doesn't always work the first time, but it may work the second or the third without reboot. (Why more than once? Because it's not Haskell :S I don't really know.)

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