Option "NvAGP" "integer"
Configure AGP support. Integer argument can be one of:
0 : disable agp
1 : use NVIDIA's internal AGP support, if possible
2 : use AGPGART, if possible
3 : use any agp support (try AGPGART, then NVIDIA's AGP)
So that would make Option "DPMS" "1" the working part?
Mind you, changing the value in the xorg.conf isnt enough. The kernel and the nvidia module both have to be redone to actually change the setting.
Also remember that whenever changing anything with the AGP stuff, the system has to be completely rebooted.
has to produce an according output, like:
AGP Rate: 4x
Fast Writes: Disabled