Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a problem with my fresh installed Ubuntu 12.04 LTS on my Dell M4600:

  • nVidia quadro 2000M
  • i7-2860 16GB ram
  • 128GB SSD Dell/Samsung
  • 750GB HDD
  • IPS RGB laptop display

When it is connected via DP++ to the external Dell U2311H monitor, it hangs on boot or when wakening from suspend. If I detach the DP cable it boots normally.

I have tried all combinations that I have found, as adding to grub:

"no splash", "boot=pci", "acpi=off", etc...

I have also changed in nVidia X settings that external monitor is the primary one and also tried to delete monitor.xml file. There is no change it hangs each time after grub. It starts to load daemons then both screens are blank and then completely hangs with beep sound.

What I discovered is if I detach the cable and wait for about 2 sec after grub starts booting and then physically connect DP cable while the Ubuntu is still booting everything works normally and I have a picture on my external screen while the laptop screen is off, just as I wanted.

Do you maybe know how to solve this issue? Thank You.

share|improve this question

The reason this problem could be occurring is because the GRUB resolution is different/higher than your monitor's resolution.

You can edit your GRUB resolution in this way:

sudo gedit /etc/default/grub

Edit line 25 and set it to 640x480px.

sudo update-grub

Now restart and see if GRUB works. If it still does not show up try pressing Shift when your GRUB loads.

share|improve this answer
Thank You for the answer but this doesn't solve the issue. Actually both displays: internal and external have identical native resolutions, and they are both IPS panels from Dell ultra-professional series. The internal display has also RGB backlighting for 100% Adobe color gamut, and therefore there is no option to turn off Optimus in BIOS. What I have noticed is that even when I unplug electric cord of the external display and leave DP++ cable connected to laptop it hangs on booting just before nVidia splash screen. So the problem is with DP++ port and ubuntu. There is no problem with windows – vladeta Jul 9 '12 at 20:41

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.