here is my post with similar problem, I cannot disable DFP-0 output and use only CRT-0 & DFP-1 with nvidia drivers:
! however you can use nouveau
drivers and then by using xrandr/(sh script)
manipulate with different outputs/modes combinations. It is working on my Ubuntu, thus I would expect it should work on FC as well. Just install nouveau and then add into blacklist nvidia drivers.
ex for using xrandr:
Run following command to find modeline details for resolution 1240×1024 (use your resolution). Modeline is required for xrandr.
$ cvt 1240 1024
# 1240x1024 59.93 Hz (CVT) hsync: 63.71 kHz; pclk: 105.50 MHz
Modeline "1240x1024_60.00" 105.50 1240 1320 1448 1656 1024 1027 1037 1063 -hsync +vsync
then do something like this:
$ xrandr --newmode "1280x1024_60.00" 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync
$ xrandr --addmode VGA-0 "1280x1024_60.00"
$ xrandr --output VGA-0 --mode "1280x1024_60.00"
Note, nouveau does not support 3D
(no compiz, ...), but as far as I know, the latest FC does support for gallium
driver (nouveau with 3D support), search for experimental packets. Keep in mind that gallium is very unstable right now...