The problem lies within the modeline, horizontal sync, and vertical refresh values located in the xorg.conf configuration file. Open the xorg.conf file using the method above and scroll down until you find HorizSync and VertRefresh. Change the values and append the line as follows:
Code:
HorizSync 60-61
VertRefresh 72-78
ModeLine "1024x768" 78.8 1024 1097 1100 1305 768 770 792 803 +hsync +vsync
If you end up unable to access a command line whatsoever to make the changes, try pressing command-F1 (or some combination with F1) to get to a command line and enter the following:
Code:
sudo -s
killall gdm
vi /etc/X11/xorg.conf****#or whatever your favorite editor may be. Edit away and save the file.
gdm****#or "startx" without the quotes if gdm doesn't start with this method or "kdm" if you use it.
The proper configuration for the CRT iMacs tend to differ from model to model (the particular modeline mentioned is for my old Rev. D iMac), so you may need to sit down and fiddle with the numbers (e.g. I tend to change 1305 to 1303 on different distros that, oddly enough, treat that value differently). This problem has been documented here and there and I was fortunate enough to come across an xf86config file for my rev. D iMac that, lo and behold, didn't center the screen completely. So, basically change the values and append the modeline, then fiddle with the values. With this method, you're stuck with 1024x768, but with more configuration you should be able to get 800x600 and any other resolutions to work for you. If you have any questions about tweaking or if my wordy instructions are muddy, don't hesitate to pm me
. Good luck!