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Re: Two display anomalies



On Tuesday 06 September 2005 23:01, Matthew Saltzman wrote:
> > 1) Try lowering the vertical refresh to 60 Hz.  I'm not familiar with
> > that display, but both the Dell and the Viewsonic recommend 60 Hz.
>
> Is this an xorg setting?  The refresh rates are what is selected when I
> run system-config-display.  There doesn't seem to be a way to set this in
> the monitor menu.  How would I set it?

If you set a generic LCD you are most likely going to run at 60Hz... 

in the KDE Control Panel you have under peripherals-> display the resolution 
and refresh rate right there.... Not sure about gnome but I bet its just as 
easy... 
If you want to use the command line you can do it as: If you want to make sure 
you'll have to look at the /var/log/Xorg.0.log file... read it from the 
bottom... You should see things like "Setting Mode" or "Screen size 
determined as" ... that's the resolution you're running at (you can also run 
xwininfo -root to get that). Scroll further up and you'll see the "Default 
mode" - match up with the resolution you determined and you'll see your 
refresh rate... 

> > 2) Are the vertical and horizontal rates the same between Windows and
> > FC4?
> >
> > Are they the same laptop?
> >
> > If you answered yes to both then I'm stumped.
>
> Yes, it's the same laptop running WinXP and FC4 and FC3 with several
> different kernels.
>
> > But...
> >
> > If the refresh rates are not same then adjust FC4 to the same as
> > Windows.
> >
> > The problem sounds like a bad/low quality cable. Cable performance will
> > get worse as the refresh rates go up.  Could also be a grounding problem
> > inducing hum in the video signal.
> >
> > If Windows and FC4 are not running on the same laptop then I would
> > suspect a hardware problem with the FC4 laptop.
>
> That's two suggestions for the cable.  I will try some others, but it's
> not clear why the same projector and same cable and same hardware behaves
> differently when I use different software.
>

Again check the refresh rates... Often you get good results at like 
1024x768/75Hz but at the same resolution but 85Hz the picture quality is much 
lower...

Peter.


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