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I have a 22'' display from HP (w2207h) connected to my laptop (a Dell Mini 10v or 1011) through a VGA switch (a share this screen with a desktop computer and a Nintendo Wii). My problem is that I can't set a higher resolution than 1024x768 (4:3) in my external display. I can only set a lower resolution (800x600 and 4:3). I used it before with Ubuntu and I had no problem with the screen resolution so I think the problem is the VGA switch. Does anybody knows how to fix this problem? Does anybody knows how I can start?

This is a screenshot of my screen configuration. The green one is the HP display and the word you can read on it is "unknown". Yes, it's in spanish. Thank you very much.

Screen configuration window Ubuntu 11.10

More information: The graphic adapter of my Dell Mini laptop is Intel945GSE UMA.

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I forgot to say that the native resolution of my HP display is 1650 x 900. Thank you. –  jefesuarez Oct 27 '11 at 22:49
    
More info. The second display is listed as unknown in the monitors/screens/displays window. –  jefesuarez Oct 28 '11 at 0:08

2 Answers 2

The same occurs to me. You must add the resolution with:

xrandr --newmode <ModeLine>

To know the ModeLine of your resolution, do this:

$ cvt 1650 900

You will get some like this:

# 1656x900 59.93 Hz (CVT) hsync: 55.98 kHz; pclk: 122.25 MHz
Modeline "1656x900_60.00"  122.25  1656 1752 1920 2184  900 903 913 934 -hsync +vsync

Then, copy the information after the word “Modeline” into the XRandR command:

$ xrandr --newmode "1656x900_60.00"  122.25  1656 1752 1920 2184  900 903 913 934 -hsync +vsync

After the mode is entered, it needs to be added to the output:

xrandr --addmode VGA1 1656x900_60.00

Now you have the new resolution :-)

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what am i gonna replace VGA1 with ? - solved: xrandr to see what the output names are –  kommradHomer Sep 19 at 7:15

If you think the problem may be the VGA switch, why don't you try plugging the monitor in directly?

Also, there's a known problem with the video chipset on many netbooks, where the combined screensize cannot exceed 2048 pixels in any dimension. So if your laptop's is 1024 pixels wide, you can only add another display of up to 1024 pixels wide.

To check for this, open a terminal and use this command:

lspci

if you see "Intel Corporation: N10 Family Integrated Graphics Controller" then your system is affected by this problem.

This is caused by some driver limitations in Ubuntu, here's the bug report for this:

https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/830949

This is why, if you try to set a higher resolution, you'll get a message saying that you need to fit all monitors within 2048x2048 pixels. Unfortunately there's no real solution to this but I can suggest two workarounds:

  1. Arrange the monitors one on top of the other. Thus it's the vertical resolution that's limited, and 600+900=1500 which is lower than 2048, thus you'll be able to use both monitors.
  2. Use Unity-2d, I think the limitation does not affect it.

Note that if you try to set the resolutions via the commandline, you'll bypass the "protection" against setting an invalid resolution. This will not work and your system will become unusably slow. If this happens, just reboot it.

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