Bug#668828:

[Jeroen Diederen <jjhdiederen@zonnet.nl>]

ok, my final solution to getting nouveau to work properly on the iMac G5 
20 inch is to use the following xorg.conf file. Note that I had to make 
a virtal desktop area of 1680x1680.

Section "Device"
    Identifier    "FX5200"
    BusID        "PCI:240:16:0"
    Driver          "nouveau"
    Option    "Monitor-VGA-1" "VGA_Port"
    Option    "Monitor-DVI-D-1" "DVI_Port"
    Option    "Monitor-TV-1" "TV_Port"
EndSection

Section "Monitor"
    Identifier    "DVI_Port"
EndSection

Section "Monitor"
    Identifier    "VGA_Port"
    Option    "Ignore" "true"
EndSection

Section "Monitor"
    Identifier    "TV_Port"
    Option    "Ignore" "true"
EndSection

Section "Screen"
    Identifier    "Default Screen"
    Device        "FX5200"
        DefaultDepth    24
           SubSection       "Display"
             Depth            24
         Virtual 1680 1680
           EndSubSection
EndSection

Section "ServerLayout"
    Identifier    "Default Layout"
    Screen        "Default Screen"
EndSection