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I have a laptop running Fedora 15, Gnome 3.0.1, and Mobile Intel® GM45 Express Chipset. I have a VGA monitor connected to it, as well as a DisplayPort to DVI adapter to connect a second monitor. Both monitors are detected by the system and I can use them individually, but not both at the same time. Both monitors are the same.

When I try to activate the second monitor using System Settings -> Display I've seen different behaviors.

  • Either the images (from the 3 screens) get overlapped on the first 2 screens, jumbled up.
  • Or one of the screens (laptop or monitor) stays active but becomes invisible. Meaning the screen is dark, but the mouse travels over there and there are windows over there.
  • As well as this:

xrandr --output VGA1 --mode 1680x1050 --rate 60
xrandr: cannot find crtc for output VGA1

Error which occurs with either of the inactive monitor.

Here's the output of xrand:

xrandr 
Screen 0: minimum 320 x 200, current 3120 x 1050, maximum 8192 x 8192
LVDS1 connected 1440x900+1680+0 (normal left inverted right x axis y axis) 303mm x 190mm
   1440x900       60.0*+   40.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 433mm x 271mm
   1680x1050      60.0*+
   1280x1024      75.0     60.0  
   1280x960       60.0  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 connected (normal left inverted right x axis y axis)
   1680x1050      60.0 +
   1280x1024      75.0     60.0  
   1280x960       60.0  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
HDMI2 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)

What else should I try to have all 3 displays active at the same time? Is it possible?

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1 Answer 1

up vote 2 down vote accepted

If you look at the chipset datasheet, there are only two display planes and display pipes (see pp. 78–79). You can also take a look at the tables on pp. 86–87. So, you've hit a hardware limitation.

You may be able to get it working if two of the displays are displaying the same thing, with the exact same settings (same image, resolution, refresh rate, bit depth, etc.).

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