Here is my xorg.conf for the Matrox G200 Quad configuration. I hope this helps people as it was quite the uphill battle…
# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by failsafeDexconf, using
# values from the debconf database and some overrides to use vesa mode.
#
# You should use dexconf or another such tool for creating a “real” xorg.conf
# For example:
# sudo dpkg-reconfigure -phigh xserver-xorg
Section “InputDevice”
Identifier “Generic Keyboard”
Driver “kbd”
Option “XkbRules” “xorg”
Option “XkbModel” “pc105″
Option “XkbLayout” “us”
EndSection
Section “InputDevice”
Identifier “Configured Mouse”
Driver “mouse”
Option “Protocol” “auto”
Option “Emulate3Buttons” “true”
Option “CorePointer”
# Option “Device” “/dev/input/mice”
# Option “AlwaysCore” “true”
# Option “ZAxis Mapping” “4 5″ #for mouse scroll
EndSection
#Section “Module”
# Load “glx”
# Load “GLcore”
# Load “dri”
# Load “v4l”
#EndSection
####################
# Display 0 – 09:00.0 [ACER AL1916W]
############################################################
Section “Device” #
Identifier “Device0″
Boardname “Matrox Millennium G200 QuadHead”
Busid “PCI:9:0:0″
Driver “mga”
Vendorname “Matrox”
VideoRam 4096
EndSection
Section “Monitor” #
Identifier “Monitor0″
ModelName “ACER AL1916W”
HorizSync 30-82
Vertrefresh 56-76
Option “DPMS”
Modeline “1440×900″ 106.47 1440 1520 1672 1904 900 901 904 932 -HSync +Vsync
# Modeline “1440×900_60.00″ 106.47 1440 1520 1672 1904 900 901 904 932 -HSync +Vsync
# ModeLine “1024×768_GM” 60.00 1024 1048 1184 1328 768 771 777 806 -Hsync -Vsync
EndSection
Section “Screen” #
Identifier “Screen0″
Device “Device0″
Defaultdepth 24
Monitor “Monitor0″
SubSection “Display”
Modes “1440×900″
Depth 24
EndSubSection
EndSection
####################
# Display 1 – 09:04.0 [ACER AL1916W]
############################################################
Section “Device” #
Identifier “Device1″
Boardname “Matrox Millennium G200 QuadHead”
Busid “PCI:9:04:0″
Driver “mga”
Vendorname “Matrox”
VideoRam 4096
EndSection
Section “Monitor” #
Identifier “Monitor1″
ModelName “ACER AL1916W”
HorizSync 30-82
Vertrefresh 56-76
Option “DPMS”
Modeline “1440×900″ 106.47 1440 1520 1672 1904 900 901 904 932 -HSync +Vsync
# Modeline “1440×900_60.00″ 106.47 1440 1520 1672 1904 900 901 904 932 -HSync +Vsync
# Modeline “800×600_GM” 38.22 800 832 912 1024 600 601 604 622 -HSync +Vsync
# Modeline “GM” 75.00 1024 1048 1184 1328 768 771 777 806 -Hsync -Vsync
EndSection
Section “Screen” #
Identifier “Screen1″
Device “Device1″
Defaultdepth 24
Monitor “Monitor1″
SubSection “Display”
Modes “1440×900″
Depth 24
EndSubSection
EndSection
####################
# Display 2 – 09:08.0 [SAMSUNG SYNCMASTER 914V]
############################################################
Section “Device” #
Identifier “Device2″
Boardname “Matrox Millennium G200 QuadHead”
Busid “PCI:9:08:0″
Driver “mga”
Vendorname “Matrox”
VideoRam 4096
EndSection
Section “Monitor” #
Identifier “Monitor2″
ModelName “SAMSUNG SYNCMASTER 914V”
HorizSync 30-81
VertRefresh 56-75
Option “DPMS”
Modeline “1280×1024″ 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
# Modeline “1280×1024_60.00″ 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
# ModeLine “1024×768_GM” 75.00 1024 1048 1184 1328 768 771 777 806 -Hsync -Vsync
# Modeline “800×600_GM” 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync
EndSection
Section “Screen” #
Identifier “Screen2″
Device “Device2″
Defaultdepth 24
Monitor “Monitor2″
SubSection “Display”
Modes “1280×1024″
Depth 24
EndSubSection
EndSection
####################
# Display 3 – 09:0c.0 [HANNS-G HC194D]
############################################################
Section “Device” #
Identifier “Device3″
Boardname “Matrox Millennium G200 QuadHead”
Busid “PCI:9:12:0″
Driver “mga”
Vendorname “Matrox”
VideoRam 4096
EndSection
Section “Monitor” #
Identifier “Monitor3″
ModelName “HANNS-G HC194D”
HorizSync 31-81
VertRefresh 56-75
Option “DPMS”
Modeline “1280×1024″ 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
# Modeline “1280×1024_60.00″ 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
# ModeLine “1024×768_GM” 75.00 1024 1048 1184 1328 768 771 777 806 -Hsync -Vsync
# Modeline “800×600_GM” 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync
EndSection
Section “Screen” #
Identifier “Screen3″
Device “Device3″
Defaultdepth 24
Monitor “Monitor3″
SubSection “Display”
Modes “1280×1024″
Depth 24
EndSubSection
EndSection
Section “ServerLayout”
Identifier “Default Layout”
Screen “Screen0″ 0 0
Screen “Screen1″ RightOf “Screen0″
Screen “Screen2″ Above “Screen1″
Screen “Screen3″ Above “Screen0″
InputDevice “Generic Keyboard”
InputDevice “Configured Mouse”
Option “Xinerama” “true”
EndSection
Section “ServerFlags”
Option “IgnoreABI” “True”
EndSection
