Si ça peut aider, je donne mon xorg.conf, bon j'ai du nVidia. par contre.
# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 280.11 (mockbuild@) Sun Jul 31 17:48:13 EDT 2011
# RPM Fusion - nvidia-xorg.conf
Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
EndSection
Section "Files"
ModulePath "/usr/lib64/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib64/xorg/modules"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "keyboard"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "Videocard0"
SubSection "Display"
Modes "nvidia-auto-select"
EndSubSection
EndSection