Hi, do you have the nvidia driver installed?...if not there is plenty of info on this site about installing it.
Does fedora use xfree or xorg?
You can set the default resolutions with either of those files within the screen section, this is a snippet from my /etc/X11/xorg.conf
Code:
# "1024x768" is also a conservative usable default resolution. If you
# have a better monitor, feel free to try resolutions such as
# "1152x864", "1280x1024", "1600x1200", and "1800x1400" (or whatever your
# card/monitor can produce)
Subsection "Display"
Depth 8
Modes "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 16
Modes "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubsection
Subsection "Display"
Depth 32
Modes "1024x768" "800x600" "640x480"
EndSubsection