Configuring three monitors with two Radeon X1600/X1650 graphics cards under Ubuntu

Posted by cpm on Super User See other posts from Super User or by cpm
Published on 2009-10-20T21:48:09Z Indexed on 2010/06/08 12:52 UTC
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I have three SyncMaster 932a monitors I want to use with two Radeon X1600/X1650 cards under Linux.

I am running X.org X Server 1.6.0, as provided by Ubuntu's Wubi installer.

After turning off mirroring, I ended up with this xorg.conf:

Section "Monitor"
        Identifier      "Configured Monitor"
EndSection

Section "Screen"
       Identifier      "Default Screen"
       Monitor         "Configured Monitor"
       Device          "Configured Video Device"
       SubSection "Display"
               Virtual 2560 1024
       EndSubSection
EndSection

Section "Device"
       Identifier      "Configured Video Device"
EndSection

The left monitor had a menu bar and a task bar, the center monitor was just desktop, and windows would maximize to the current monitor. The third monitor and second graphics card weren't being used at all.

Then I changed my configuration to manually specify each card with their PCI bus:

Section "ServerLayout"
        Identifier      "TheLayout"
        Screen          0 "Radeon Screen 1"
        Screen          1 "Radeon Screen 2" RightOf "Radeon Screen 1"
EndSection

Section "Screen"
        Identifier      "Radeon Screen 1"
        Monitor         "Configured Monitor"
        Device          "Radeon the First"
        SubSection "Display"
                Virtual 2560 1024
        EndSubSection
EndSection

Section "Screen"
        Identifier      "Radeon Screen 2"
        Monitor         "Configured Monitor"
        Device          "Radeon the Second"
EndSection


Section "Device"
        Identifier      "Radeon the First"
        Driver          "radeon"
        BusID           "PCI:1:0:0"
EndSection

Section "Device"
        Identifier      "Radeon the Second"
        Driver          "radeon"
        BusID           "PCI:2:0:0"
EndSection

Section "Monitor"
        Identifier      "Configured Monitor"
EndSection

Now both the left and right monitors have task bars and menu bars. Windows cannot be dragged from the first two monitors to the third monitor. Also, maximizing in the left or center window fills both monitors.

I also tried adding Option "Xinerama" "true" to the ServerLayout section. X11 wasn't able to start up.

I want to:

  1. Allow moving windows along all three monitors.
  2. Maximizing only fills the current monitor.
  3. Either have menu/task bars on only the left monitor or all three monitors

How can I make this possible?

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