FC2 - only 85Hz WORKS

[Janis K]

hello Jonathan

THANK YOU!!! i changed the pixel clock as you calculated and now the refresh
rate is 1024x768 @ 100Hz :)))))

have a nice weekend :)

bye

----- Original Message ----- 
From: "Jonathan Rawle" <jr36 at leicester.ac.uk>
To: <fedora-list at redhat.com>
Sent: Friday, May 21, 2004 4:00 PM
Subject: Re: FC2 - only 85Hz


> Janis K wrote:
>
> > it shows this:
> >
> > "1024x768"  94.50  1024  1072  1168  1376   768  769  772  808  +hsync
> > +vsync
> >
> >>
> >> The first number after "1024x768" is the "Pixel clock" in MHz. The
> > formulas
> >> connecting the different frequencies are:
> >>
> >> Horizontal sync = Pixel clock / HTotal
> >> Vertical sync = Horizontal sync / VTotal
> >
> > so my pixel clock shows 94.50 and xvidtune shows that HTotal = 1376 and
> > Vtotal = 808 (is it in Hz?)
> > and to calculate with the formulas i have this:
> >
> > Horizontal sync = pixel clock / Htotal = 94.50 / 1376 =
0.068677325581...
> > Vertical sync = Horizontal sync / VTotal = 0.068677325581 / 808 =
0.000085
> >
> > is it so? I think I'm doing something wrong with these Hz/kHz/MHz ... I
> > have no idea about this and I am terribly afraid to demage my monitor
> >
>
> The pixel clock is 94.50 MHz = 94500000 Hz
> (the correct units are shown in the xvidtune window)
>
> If you want 100 Hz Vertical sync, you need
> Horizontal sync = 100 Hz x 808 = 80800 Hz
> (that's 80.8 KHz, so make sure your monitor can handle this!)
>
> Pixel clock = 80800 Hz x 1376 = 111180800 Hz = 111.18 MHz
>
> So replace 94.50 with 111.18 in your Modeline.
>
> As long as you have the VertRefresh and HorizSync limits right in
xorg.conf,
> there shouldn't be any risk of damaging your monitor. If the new mode you
> have defined is incompatible, X will simply choose a mode with a lower
> refresh rate instead (i.e. it'll still be on 85 Hz) If that happens, try a
> lower pixel clock.
>
> Jonathan
>
>
>
>
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