[NBLUG/talk] monitor resolution question

Justin Thiessen thiessen at sonic.net
Sat Aug 23 14:24:00 PDT 2003


On Sat, 23 Aug 2003, Lynn Sears wrote:

> I just installed RH 7.2 and would like to change the monitor res.I
> have looked around in /etc/X11/X86config and I see lots of commented
> out settings and I haven't got a modem running on that machine or I
> could send a copy of my file.  I'm guessing I'm supposed to edit the
> X86 config file but there are many sections. Would someone please
> give me some help or a link to some help. I'm new at linux
> configuration so have mercy on me ie I need pretty dumbed down
> instruction. Thanks in advance and please let me know if I'm using
> the correct list for this request. thanks..lynn

Heya,

I run slackware instead of Redhat, so there are probably some differences.
On my system, "man XF86Config" turns up a nice man page describing the
syntax and keywords of the config file.  If the corresponding config file
under Redhat is "X86config", then you might try "man X86config" and see
what comes up.  In any case, there is lots of useful info at

http://www.xfree86.org

Look under the "Support, Documentation and Resources" section.

As others have pointed out, the main thing you need to do is change the
list of "Modes" under the "Screen" section.  For each desired bit depth
(8-bit, 16-bit, 24-bit, etc.), change the list to the set of resolutions
you desire.  As long as they are standard VESA modes (640x480, 800x600,
1024x768, etc.), X11 should be able to provide you with a suitable
display, provided that your monitor can handle the desired resolutions,
and X knows the correct specs for your monitor.

These specs should be listed earlier in a section that looks something
like:

Section "Monitor"
    Identifier  "nec multisync 5d"
    HorizSync  30-66
    VertRefresh 50-90
EndSection

You should be able to check that the ones in your config file match those
listed in your monitor's manual or on the manufacturer's site, or, failing
this, in a monitor database online, like:

http://www.monitorworld.com
http://www.griffintechnology.com

I do not know if X is now capable of generating modelines for arbitrary
resolutions, like 1400x1050, or for wide-aspect-ratio screens.  If not,
you can always use something like:

http://koala.ilog.fr/cgi-bin/nph-colas-modelines

And generate your own modelines

Or, if you're a nut like me, you can go through

http://ldp.kernelnotes.de/HOWTO/XFree86-Video-Timings-HOWTO/

to do this.

You will almost certainly want to use xvidtune to tweak these, and you can
guarantee that you get the highest possible refresh rates this way.

**************************************

===========>I know this sounds like lots of work.<=============

Primarily, you should make sure that you know what modes your monitor is
capable of, (look in the manual), and edit the "Screen" section of your
config file to include these.  If this doesn't work, then check whether
the monitor specs are properly listed in the config file.

Under slackware, I always just run xf86config first and it sets up most of
this for me.  Xconfigurator may do all of this for your; I'm not familiar
with it.  If I'm making this waaaaaay too complicated, let me know, Redhat
gurus.

In any case, if this doesn't work, feel free to get back to us.  I've done
everything from using slack's automated config tools, to writing modelines
by hand, to hooking up fixed-frequency monitors, to setting up multiple
monitors in Xinerama on multiple brands of video cards, and I'd be glad to
try and help.  Hopefully the chasm between Redhat's config system and
slackware's config system won't get too much in the way.

Justin Thiessen
thiessen at sonic.net





More information about the talk mailing list