This is a copy from another website. I want to show a different that I'd made to my Xorg.conf. Ok now you can see both of a different. I think I did in simple way.
Firstly, let check out what they're recommend:

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup
sudo gedit /etc/X11/xorg.conf
sudo dpkg-reconfigure xserver-xorg

Edit xorg.conf and put correct values to your xconf.org's Monitor section. Something like this:

Code:

Section "Monitor"
Identifier "CM752ET"
HorizSync 31-101
VertRefresh 60-160
EndSection

Adding custom modeline

Now, if you know what your monitor can do, for example 1024x768@75Hz (edit: choose decent resolution / refreshrate), you can open another terminal window (keep xorg.conf open in gedit) and enter:

Code:

gtf horizontalresolution verticalresolution refreshrate

for example:
gtf 1024 768 75

Copy paste the output to your Monitor section.

Code:
# 1024x768 @ 75.00 Hz (GTF) hsync: 60.15 kHz; pclk: 81.80 MHz
Modeline "1024x768_75.00" 81.80 1024 1080 1192 1360 768 769 772 802 -HSync +Vsync

Now you can select the defaul resolution and colordepth by tweaking the Screen section. It should look something like this:

Code:
Section "Screen"

Identifier "Default Screen"
Device "NVIDIA Corporation NV34 [GeForce FX 5200]"
Monitor "CM752ET"
DefaultDepth 16
SubSection "Display":
Depth 16
Modes "1280x1024" "1024x768"
EndSubSection
EndSection

If that doesn't work, try fixing the xorg.conf or get back to your original by copying the backup over your changed one with:

Code:

sudo cp /etc/X11/xorg.conf_backup /etc/X11/xorg.conf

How to adjust position of your screen?

open terminal(Applications->Accessories->Terminal), run xvidtune (type: "xvidtune"), adjust the screen and hit Show-button. You'll see a line with something like this on the terminal screen:

Code:

"1280x1024" 157.50 1280 1332 1492 1728 1024 1025 1028 1072 +hsync +vsync

Next you should:

Code:

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup
sudo gedit /etc/X11/xorg.conf

In Monitor section, add the above line with a prefix "Modeline", like this:

Code:

Modeline "1280x1024" 157.50 1280 1332 1492 1728 1024 1025 1028 1072 +hsync +vsync

That should do it. There should be no need to restart X if you did make the change (hit Apply in xvidtune), but you should test that this new change works. Hit ctrl+alt+backspace to restart X. If it doesn't work, you can copy back the old configuration file using:

Code:

sudo /etc/X11/xorg.conf_backup /etc/X11/xorg.conf

and restart X using:

Code:
sudo /etc/init.d/gdm start

Ok, this is what I had done. Ok, now you can see all the different from one guide (from other website) that I found. IIn this case, I only change from:



sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup =to make back up
sudo dpkg-reconfigure xserver-xorg = to reconfigure
sudo gedit /etc/X11/xorg.conf = to edit

Code:
Section "Screen"

Identifier "Default Screen"
Device "NVIDIA Corporation NV34 [GeForce FX 5200]"
Monitor "CM752ET"
DefaultDepth 16
SubSection "Display":
Depth 16
Modes "1280x1024" "1024x768"
EndSubSection
EndSection

to my xorg like this:

Section "Screen"
Identifier "Default Screen"
Device "Configured Video Device"
Monitor "Configured Monitor"
Defaultdepth 16
SubSection "Display"
Depth 16
Modes "1280x1024" "1024x768"
EndSubSection
EndSection


Simple and fast, isn't it??

You can refer my xorg.conf. (I insert "default" and "configured" only so it can use default setting) You can copy and paste and try it but make sure to back up before you do this. Restart pc to get a new resolution (System-Preferrence-Screen Resolution). This is what happen after I restarted.

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
EndSection

Section "Device"
Identifier "Configured Video Device"
Boardname "vesa"
Busid "PCI:1:0:0"
Driver "vesa"
Screen 0
EndSection

Section "Monitor"
Identifier "Configured Monitor"
Vendorname "Plug 'n' Play"
Modelname "Plug 'n' Play"
modeline "640x480@60" 25.2 640 656 752 800 480 490 492 525 -vsync -hsync
Gamma 1.0
EndSection

Section "Screen"
Identifier "Default Screen"
Device "Configured Video Device"
Monitor "Configured Monitor"
Defaultdepth 16
SubSection "Display"
Depth 16
Modes "1280x1024" "1024x768"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
screen 0 "Default Screen" 0 0
EndSection
Section "Module"
Load "glx"
Load "GLcore"
Load "v4l"
EndSection
Section "ServerFlags"
EndSection