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Re: [vox-tech] Re: vox-tech digest, Vol 1 #417 - 1 msg
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Re: [vox-tech] Re: vox-tech digest, Vol 1 #417 - 1 msg

begin Robin Snyder <resnyder@ucdavis.edu> 
> A friend pointed out that scanpci and lspci say that I *do* have an mga
> chipset and not an ATI card, no matter what the company that assembled the
> machine told me.

why not open the machine and take a look?

> He was able to get an XF86Config-4 file going that sort
> of works for me.  However, for curiosity's sake, I installed discover (I
> had the other two already) and reran dpkg-reconfigure xserver-xfree86,
> choosing the mga module for the graphics card.  The resulting
> configuration file didn't work at all--startx couldn't run (config file
> and startx error messages below, for those who care).  As I said, X is
> sort of running now; however, there is an annoying high frequency flicker
> to the screen.  I assume this is some sort of refresh rate problem?
> Gnome-terminal also crashes as soon as I try to start one.  Has anyone
> else had this problem under X4?  The error message is uninformative
> (floating point exception).

robin, your posts are very difficult for me to read.

and a little more time discussing your situation would be nice too.  you
went from "X doesn't work at all" to "as i said it's sort of running".
i'm not exactly sure how it started to work again.

also, paragraphs to separate ideas would help me visualize what you're

about your problem:

there's actually many ways to increase refresh rate.  unfortunately,
this makes it difficult to discuss.  i used to do this sort of thing all
the time under X3, but i've never seen a problem as persistant as yours
under X4.

since the answer is so long winded, i wanted to know if there's anything
on the web which is less technical than ESR's "video mode timing howto"
yet still useful.   i googled for "linux X monitor flicker" and found
this link:


it was written for X3, but the concepts are all the same.

there are a couple of things you can do to experiment.

1. try raising the maximum vertrefresh rate in the monitor section of
   your XF86Config-4 file.  i wouldn't push it past 10% of the current
   max value.

2. try using a lower screen resolution.  if your video card's dot clock
   is the bottleneck, this should help.

3. another thing that could help if your video card's dot clock is the
   bottleneck is lower the color depth.  try using 16bpp, which should
   be fine if you don't play games or do alot of graphics stuff.

use xvidtune to look at your refresh rate before and after your changes
to see if they help.

btw, are you using a newish monitor and new video card?  if so, there's
no excuse for this stuff to be happening.

also, i noticed this in your XF86Config-4 file:

   Section "Monitor"
      Identifier      "Miserable Monitor"
      HorizSync       30-84
      VertRefresh     50-75
      Option          "DPMS"

who called it "miserable monitor"?  if the monitor is truly this
miserable, there's much you can do about it.  your vertical refresh
rate is surprisingly low for a newish monitor.   as a first line of
attack, i would do some websearching and make sure these numbers are
correct.  you can find them on your monitor's "spec sheet".

hope something here is useful.  you'll almost certainly need to read a
little bit to understand all of it.

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