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I am running 12.04 on a Toshiba Portege laptop. The graphics card is an Intel 945GM/GMS. The 2nd monitor is an Asus (Ancor Communications 22"). When I connect the monitor to the computer the monitor is recognized but nothing is displayed. There is only a black screen. The monitor is not receiving any signal from the computer.

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Ubuntu 12.04 doesn't automatically enable the external monitor, from my testing. Did you try enabling it in the Display settings and giving it a resolution to display? (Settings -> Display) – Thomas Ward Jul 4 '14 at 2:09
@ThomasW., in the display settings I did set the button to "On". – Kevin Jul 4 '14 at 3:26
I followed these steps at another answered question and it seemed to correct the problem: – Kevin Jul 4 '14 at 4:00

Is it Possible that you have a graphics card that only supports one monitor? Or is your laptop limiting the graphics card? Check to see if the monitor will work like you want it to in windows.

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Don't have Windows. I previously used the monitor on Macbook Pro. – Kevin Jul 4 '14 at 3:27
Have to add. It looks like the secondary monitor is not receiving any signal from the computer although the computer does recognize that it is plugged in. – Kevin Jul 4 '14 at 3:29
"not receiving any signal" does this mean that the screen is blank, or does it flash some sort of "no signal" notification? – Blaine Jul 5 '14 at 4:47
it was the graphics card. I updated the driver and seems to work. – Kevin Jul 5 '14 at 4:55

try going into 'Setting -> Display' and select the Asus monitor.


After more research I believe this is related to a bug with Intels 945GM chipset.

I also found one post that said they were able to get the monitor to work by:

  1. disabling the 'visual effects'
    • System > Appearance > Visual Effects is set to None
  2. connecting monitor
  3. Settings -> Display
  4. clicking 'detect monitor'
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The monitor is set to on after I click the 2nd monitor. If I turn off the laptop screen the laptop screen will go black and the monitor also stays black. I assume I am getting a message to revert back to the previous configuration because after less than a minute it will go back to the previous setting. It looks like the monitor is not getting any signal even though the OS is recognizing that the monitor is plugged in. – Kevin Jul 4 '14 at 3:29
This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post. – Luís de Sousa Jul 4 '14 at 13:16

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