non voici un exemple de fichier dual, moi j'utilise un portable dell inspiron 9300 avec les driver nvidia beta
Section "ServerLayout"
Identifier "Default Layout"
Screen "Dual" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Synaptics" "CorePointer"
EndSection
Section "Files"
ModulePath "/usr/lib/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib/xorg/modules"
FontPath "unix/:7100"
EndSection
Section "Module"
SubSection "extmod"
Option "omit xfree86-dga" # don't initialise the DGA extension
EndSubSection
Load "glx"
Load "dri"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "fr"
EndSection
Section "InputDevice"
Identifier "Synaptics"
Driver "synaptics"
Option "Device" "/dev/input/mice"
Option "Protocol" "auto-dev"
Option "Emulate3Buttons" "yes"
Option "LeftEdge" "120"
Option "RightEdge" "830"
Option "TopEdge" "120"
Option "BottomEdge" "650"
Option "FingerLow" "14"
Option "FingerHigh" "15"
Option "MaxTapMove" "110"
Option "VertScrollDelta" "20"
Option "HorizScrollDelta" "20"
Option "MinSpeed" "0.3"
Option "MaxSpeed" "0.75"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "LCD Panel 1920x1200"
Option "dpms"
EndSection
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "Videocard vendor"
BoardName "nVidia Corporation NV41.8 [GeForce Go 6800]"
Option "AddARGBGLXVisuals" "True"
Option "RenderAccel" "true"
Option "noLogo"
EndSection
Section "Screen"
Identifier "Dual"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView " "on"
Option "ConnectedMonitor" "CRT,DFP"
Option "TwinViewOrientation" "Clone"
# Option "TwinViewOrientation" "LeftOf"
Option "MetaModes" "1280x1024,1920x1200"
SubSection "Display"
Depth 24
Modes "1920x1200"
EndSubSection
EndSection
Section "Extensions"
Option "Composite" "Enable"
EndSection