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== Introduction ==
This Howto is intended for those who have problems with resolution or
screen refresh rate (flickering), regardless of how they got to this
situation. A possible reason for this is that your
hardware (video adapter/monitor) may not have been detected properly.

One solution will work for one person and another solution will work for
someone else. I hope to provide several different solutions here, ranked in
decending order from what I have seen to be the most popular and successful
solution to those solutions that have helped only a few. This way, hopefully
it will provide an answer for everyone. Let's start with the most popular fix.

For ATI Users I recommend reading the ATI - Refresh Rate & Resolution Quickfix
part on the bottom of this Page.

== Desktop Setting ==
First step that most people miss is to run 'System', 'Preferences', 'Screen Resolution'. Be sure to
pick your preferable resolution and refresh rate for your desktop. From there, click the option that states
'Make default for desktop only'. Now, restart and login again.
If that doesn't work, look below.

== Undetected Monitor Specs ==
Open the file {{{/etc/X11/xorg.conf}}} in your favorite text editor. I'll assume
you are using {{{nano}}} for an editor as it is fairly straight forward: {{{
sudo nano /etc/X11/xorg.conf
}}}

Now look for a section in that file called {{{Section "Monitor"}}}. Once you find
this section, look at the lines of text between {{{Section "Monitor"}}}
and {{{EndSection}}}. There should be two lines in there that begin with the
words {{{HorizSync}}} and {{{VertRefresh}}}. If those lines don't appear there,
don't worry. There is a good chance that we've found the problem already!

You will need to gather two bits of information for your monitor now, either
from your Monitor User's Manual, the command line, or from online.
Finding these values usually just involves searching [[http://www.google.com|Google]]
with the model of your monitor. One extensive list is at the
[[http://forum.linux-sevenler.org/index.php/topic,866.0.html?PHPSESSID=238b3fe295b404d31020ac23777c8a6f|Lapis forum]]

We need the horizontal sync frequency
(usually measured in kHz) and the vertical refresh rate (usually in Hz).
Both of these values are typically given in a
range such as "30-98 kHZ" or "50-160 Hz".

Alternatively, if your monitor supports it, you can just run
the following command (install the 'xresprobe' package if the command is not available): {{{
sudo ddcprobe | grep monitorrange
}}}

The first two values returned are your HorizSync rates, the second pair is your VertRefresh values.

There are two ways to enter your monitor information into the file. One way
is to run the following commands which will regenerate the file and ask you
for the values in the process: {{{
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.custom
md5sum /etc/X11/xorg.conf |sudo tee /var/lib/xfree86/xorg.conf.md5sum
sudo dpkg-reconfigure -plow xserver-xorg
}}}

The second way is to simply add those values to our {{{/etc/X11/xorg.conf}}}
file with a text editor. But first, lets make a backup of that file just in
case an error is made: {{{
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
}}}

Editing this file so that it works involves adding two extra lines to the {{{Section "Monitor"}}} section of that file. For example, mine is shown below.

{{{
Section "Monitor"
     Identifier "FLATRON 995F"
     Option "DPMS"
     HorizSync 30-96
     VertRefresh 50-160
EndSection
}}}

||<tablestyle="text-align: justify; width:100%; " style="border:none;" 5%>{{attachment:IconsPage/PicDocs.png}} ||<style="padding:0.5em; border:none;"> ''Don't __change__ anything that is written in the file for now. Just add the two lines. The snippet from my file is just an example and may not apply to your hardware. More importantly if your monitor is not detectable, the Identifier will be called `Generic Monitor`. In which case, don't change the Identifier to anything else otherwise X will fail to load and report that it can't find the a Monitor.''||

Now save the file, close all open applications, and press {{{CTRL-ALT-Backspace}}}
to restart X. Assuming all goes well, you will be prompted to log into your
session again.

Also if you have an issue where only 800x600 is available in the dropdown for screen resolution, then modifying the ''Modes'' line within the section in that file called {{{Section "Monitor"}}} and adding the required resolution could solve this.
{{{
        SubSection "Display"
                Depth 24
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
}}}

----
CategoryCleanup
#REDIRECT https://wiki.ubuntu.com/X/Config

FixVideoResolutionHowto (last edited 2011-11-04 22:07:48 by ckimes)