Getting S-Video out working with X on an 8800GS

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I have an 8400GS that has an S-Video out and I want to run it connected to a SDTV only (not to a CRT and TV). When I connect the card to my TV via an S-video cable without connecting the monitor at all, I can watch Linux boot on the TV. Problem for me is when I start X. The TV goes blank. If I plug in a CRT monitor, X is being displayed there rather than on the TV. If I have the TV connected and I also connect a CRT monitor, I can get into X just fine. The nvidia-settings program doesn't detect my TV at all.

I should say that if I switch out the 8400GS (PCI) for an older 6200 (AGP) everything just works without any modifications to the /etc/X11/xorg.conf at all!  I've tried adding many of the suggested lines at the following wiki page, but still, no output to X: http://en.wikibooks.org/wiki/NVidia/TV-OUT

Here is the /etc/X11/xorg.conf that works with the 6200 (AGP) but not with the 8400GS (PCI):

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
        Modes "800x600"
    EndSubSection
EndSection