I have a Dell M1530, which has Windows 7 and Ubuntu 11.10 installed on it. The screen on my laptop no longer works but the external monitor works fine, well, almost. The resolution is set to 1024x768 even though my monitor can handle 1920x1200. I've tried using xrandr but it's unable to identify my monitor, and so i can't change the external monitor settings. I get an error which goes something like "xrandr: Failed to get size of gamma for output default" and then some screen resolutions which my laptop screen supports but my external monitor only supports a few of them.

I have a feeling that this is happening because of some sort of conflict because of the broken laptop screen. I know that Windows 7 is able to detect the broken laptop screen, and this is why i have an inclining that Ubuntu is getting "confused".

Is there a solution to this or can I just unplug the laptop screen from the motherboard?

2 Answers 2


Finally got it to work! I ended up manually changing the xorg.conf file and all's good.

So first i ran

sudo nvidia-xconfig

to create a new xorg.conf file. I was hoping this would solve the problem, which it didn't. Then i found this post here and copied over this

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "DELL U2412M"
    HorizSync       30.0 - 83.0
    VertRefresh     50.0 - 61.0
    Option         "DPMS"

After a restart i went to the Nvidia settings and low and behold the correct resolutions were listed. I think I was correct in thinking that the computer was detecting the laptop's screen settings rather than the external monitor.


See you're using an Dell M1530, if I remember correct that uses the nvidia graphics card. Have you tried use the nvidia settings manager to set the right resolution? Have a look at this: Trouble recognising external monitor


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