[citizen428]

Hier die relevanten Zeilen aus meiner /etc/X11/XF86Config:

Section "Monitor"
	Identifier   "Monitor0"
# Wish we could use some probed settings here, too, but XFree4 cannot do this yet.
#	HorizSync    28.0 - 78.0 # Warning: This may fry very old Monitors
	HorizSync    28.0 - 96.0 # Warning: This may fry old Monitors
	VertRefresh  50.0 - 76.0 # Very conservative. May flicker.
# These are some Modelines that happen to work on many systems
# Especially the "1024x768" has been thoroughly tested, even on Laptops
	Modeline "640x480"     25.175 640  664  760  800   480  491  493  525 #60Hz
	Modeline "800x600"     40.12  800  848  968 1056   600  601  605  628 #60Hz
	Modeline "1024x768"    85    1024 1056 1152 1360   768  784  787  823
	Modeline "1152x864"    92    
[...hier wurde gekürzt...]
EndSection

Gentoo Linux, XFree86 4.3.0-r5

Und wegen

gentoo rocks!

Sieh dir vielleicht mal folgendes an, vielleicht hilft es dir:
http://www.cargal.org/drupal/node.php?id=76
http://www.cargal.org/drupal/node.php?id=176
http://www.cargal.org/drupal/node.php?id=186

Und vor allem auch:
http://www.cargal.org/forums/viewtopic.php?t=1252