> How can I change the refresh rate in Xwindows for a Matrox Mystique
> 4Mb card and a normal 1024x768 SVGA monitor. Xconfigurator detects the
> card and installs the SVGA server and defaults to 1024x768 32bit
> colors. That's OK, but when I start X the screen is out of sync and I
> think it's because of the refresh rate (my monitor can't handle high
> rates), so I would like to know how can I change the refresh to 56Hz.
Does "X Windows" mean XFree86, AccelX, MetroX? It makes a difference as to
how one would
go about changing that. If your card/monitor combo is capable of doing so,
MetroX's config utility will allow you to choose the refresh rate (if memory
serves). And I think that refresh rate in AccelX is determined by your
choice of monitor (and limited by your choice of video card).
XFree86, on the other hand, if you're looking at the XF86Config file, requires
that you supply the horizontal sync rate and vertical refresh rates (or ranges
of rates)
Then you develop Modelines. As far as I understand, the modelines involve
both vertical and horizontal rates and the dot clock, limited by the max
allowable dot clock (or have them automatically developed by Xconfigurator or
XF86Setup or xf86config--choose your weapon...).
In this scheme, when put in your vertical refresh rates, you are just telling
it the allowable
range or groups of ranges for those rates (same goes for horizontal sync
rates). But modeline being processed is what ultimately determines the
automatic selection of vertical and horizontal rates. There is a good
discussion of Modelines in the big fat Dr. Linux book of Red Hat's (which is
basically the Linux Bible from Yggdrasil). If you don't feel like learning
how to
calculate a Modeline, fire up the utility called "xvidtune." Fiddle around
with the settings,
and watch how your vertical and horizontal rates fluctuate. What is happening
is that
you are interactively developing a Modeline. And you can dump that modeline
to the xterm
from which you fired up xvidtune. Then you can paste it into XF86Config (you
can even call it whatever you want), and reference that new modeline from the
applicable "Screen" section of the XF86Config file.
One thing that I think you'll notice when using xvidtune, is that it is a real
give and take
sort of situation. It's not just as simple as selecting a 70 kHz vert.
refresh rate. By the
way, I think your reference to a 56 Hz refresh rate is awfully low for a
vertical rate, even if
you meant kHz instead of Hz. But the XFree86 configuration method can help
you adjust either
or both of those. Also to consider: different screen resolutions and color
depths tax
video cards and monitors differently. You may not be able to achieve the
vert. and hor. rates that you want in your current resultion or color depth.
Your monitor manual (hopefully you have one) will probably be indispensable in
setting up an optimized or customized X configuration.
I use mine every time I configure X (cause I have two different machines and
can't remember all
of those numbers for both of them!)
...I hope that I'm not swatting a fly with a sledge hammer here!
--
======================== Mike Wilkerson ==========================
"You cannot go on 'seeing through' things forever. The whole point
of seeing through something is to see something through it."
C.S. Lewis, "The Abolition of Man"
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