Its been a while.

see if you've got..

Xconfigurator

If you don't, then you'll need to run

xf86config

(should be in /usr/X11R6/bin for both)

xf86config will take a few times through before you get used to it. You can control-C out, too. :)

Addison

control-alt + and - will cycle.

If you go into a mode the monitor won't handle, and might overrun it, control-alt-backspace will kill X.

How many bitplanes are you running?

(you can start it with.. er.. been a couple years... um.. "startx --bpp32"? (or 16 or 24).

Addison