F17: what replaces xorg.conf??

[Beartooth]

	One of my F17 machines hardly ever manages to boot. It's an old 
Dell PowerEdge SC1420, and it did fine with all the previous Fedora 
releases, and fine until recently with F17. Now it hits the monitor's 
error message "input signal out of range." 

	But sometimes, if I leave it long enough, it does get to the login 
screen, and after that works normally.

	Time was when I'd've tried editing some configuration file in /
boot/grub or /etc/X11; but the only such I can find now start with "Do 
NOT EDIT" -- so I'm out of my depth.

 --
Beartooth Staffwright, Sometime Historian of Tongues
Sclerotic Squirreler, Double Retiree, Linux Convert 
No one can ever have enough books, pockets, friends, 
knives, guns, garlic, or mountains.