Matrox G450 dual-head support

Yep can do this in Ubuntu by manually customizing your /etc/X11/xorg.conf file, using the "Xinerama" option. Here is a tutorial on doing this:

http://www.paralipsis.org/2006/01/enabling-xinerama-in-ubuntu/

Thanks, Modification of /etc/X11/xorg.conf went soothly but with same results. Went to System>Preferences>Screen Resolution thinking changes needed to be made there - got "The X Server does not support the XRandR extension. Runtime resolution changes to the display size are not available." Obviously I missed something. Also upgraded to 7.04 with same results.

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg
#
# Modified for Multihead operation
# 20 Oct 2007 by John Goodman
##

Section "Files"
 FontPath "/usr/share/X11/fonts/misc"
 FontPath "/usr/share/X11/fonts/cyrillic"
 FontPath "/usr/share/X11/fonts/100dpi/:unscaled"
 FontPath "/usr/share/X11/fonts/75dpi/:unscaled"
 FontPath "/usr/share/X11/fonts/Type1"
 FontPath "/usr/share/X11/fonts/100dpi"
 FontPath "/usr/share/X11/fonts/75dpi"
 FontPath "/usr/share/fonts/X11/misc"
 # path to defoma fonts
 FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
 Load "i2c"
 Load "bitmap"
 Load "ddc"
 Load "dri"
 Load "extmod"
 Load "freetype"
 Load "glx"
 Load "int10"
 Load "type1"
 Load "vbe"
EndSection

Section "InputDevice"
 Identifier "Generic Keyboard"
 Driver "kbd"
 Option "CoreKeyboard"
 Option "XkbRules" "xorg"
 Option "XkbModel" "pc105"
 Option "XkbLayout" "us"
 Option "XkbOptions" "lv3:ralt_switch"
EndSection

Section "InputDevice"
 Identifier "Configured Mouse"
 Driver "mouse"
 Option "CorePointer"
 Option "Device" "/dev/input/mice"
 Option "Protocol" "ExplorerPS/2"
 Option "ZAxisMapping" "4 5"
 Option "Emulate3Buttons" "true"
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "stylus"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "stylus"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "eraser"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "eraser"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "cursor"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "cursor"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "Device"
 Identifier "Matrox Graphics, Inc. MGA G400 AGP"
 Driver "mga"
 BusID "PCI:1:0:0"
 Option "OldDmaInit" "True"
EndSection

Section "Monitor"
 Identifier "SyncMaster"
 Option "DPMS"
EndSection

Section "Screen"
 Identifier "Default Screen"
 Device "Matrox Graphics, Inc. MGA G400 AGP"
 Monitor "SyncMaster"
 DefaultDepth 24
 SubSection "Display"
  Depth 1
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 4
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 8
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 15
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 16
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 24
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
EndSection

Section "Screen"
 Identifier "ScreenLeft"
 Device "Matrox Graphics, Inc. MGA G400 AGP"
 Monitor "SyncMaster"
 DefaultDepth 24
 SubSection "Display"
  Depth 1
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 4
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 8
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 15
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 16
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 24
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
EndSection

Section "Screen"
 Identifier "ScreenRight"
 Device "Matrox Graphics, Inc. MGA G400 AGP"
 Monitor "SyncMaster"
 DefaultDepth 24
 SubSection "Display"
  Depth 1
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
  EndSubSection
 SubSection "Display"
  Depth 4
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
  EndSubSection
 SubSection "Display"
  Depth 8
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 15
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 16
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 24
  Modes "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
 EndSubSection
EndSection

Section "ServerLayout"
 Identifier "Default Layout"
 Screen "Default Screen"
 InputDevice "Generic Keyboard"
 InputDevice "Configured Mouse"
 InputDevice "stylus" "SendCoreEvents"
 InputDevice "cursor" "SendCoreEvents"
 InputDevice "eraser" "SendCoreEvents"
EndSection

Section "ServerLayout"
 Identifier "Multihead"
 Screen "ScreenLeft"
 Screen "ScreenRight" RightOf "ScreenLeft"
 InputDevice "Generic Keyboard"
 InputDevice "Configured Mouse"
 InputDevice "stylus" "SendCoreEvents"
 InputDevice "cursor" "SendCoreEvents"
 InputDevice "eraser" "SendCoreEvents"
EndSection

Section "ServerFlags"
 Option "xinerama" "true"
 Option "DefaultServerLayout" "Multihead"
EndSection

Section "DRI"
 Mode 0666
EndSection

Delete the first "ServerLayout" section with the "Default Layout" identifier.

You can also delete the first "Screen" section with the "Default Screen" identifier.

You also need to have two "Monitor" sections, they should look like this:

Section "Monitor"
        Identifier "Monitor0"
        ModelName "SyncMaster"
        Option "DPMS"
        HorizSync 28-80 # Replace this with correct one for SyncMaster
        VertRefresh 48-75 # Replace this with correct one for SyncMaster
EndSection

Section "Monitor"
        Identifier "Monitor1"
        ModelName "SyncMaster"
        HorizSync 28-80 # Replace this with correct one for SyncMaster
        VertRefresh 48-75 # Replace this with correct one for SyncMaster
        Option "DPMS"
EndSection

You need to look up the correct HorizSync and VertRefresh rates for your monitor and replace the numbers I've shown above, otherwise you may not be able to get all the resolutions your monitor is capable of.

Also, yeah I also have found the Screen Resolution GUI tool breaks when using with Xinerama. I don't know a workaround for that other than just specifying the resolutions you want in xorg.conf

Hope this helps,
Bryce