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Re: FC2 - only 85Hz



----- Original Message ----- 
From: "Jonathan Rawle" <jr36 leicester ac uk>
To: <fedora-list redhat com>
Sent: Friday, May 21, 2004 1:51 PM
Subject: Re: FC2 - only 85Hz


> Janis K wrote:
>
> > hello
> >
> > FC2 found my video cards as NVIDIA GeForce2 MX (generic) as it really
is,
> > and I have SONY Trinitron Multiscan E230 monitor 17'' (during the
> > installation, FC2 recognized my monitor as SONY CPD E230), but FC2
Control
> > Center shows ONLY 85Hz @ 1024x768 - why it is so?
> >
> > on WinXP my monitor works with 100Hz @ 1024x768
> >
> > how can I turn 100Hz @ 1024x768 on FC2?
> >
>
> For some reason, modes with higher refresh rates are not defined in the
> default X configuration. You need to add a ModeLine to your xorg.conf
>
> >From a terminal, run xvidtune
>
> Click "show" - a line of numbers will appear in the terminal

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

>
> Note: HTotal and VTotal are larger than the resolution of the screen, as
> indicated in xvidtune.

yes it is:

my HTotal = 1376 and Vtotal = 808
>
> You can work out what you should change the pixel clock to in order to
> obtain a 100Hz mode.
>

can you please tell me how to calculate it? I have never worked with such
thing

> Now open your /etc/X11/xorg.conf in an editor. Find the "Monitor" section
> and ensure that the specs for your monitor are correct - HorizSync (in
KHz)
> and VertRefresh (in Hz) MUST be right, or you risk damaging your monitor.
> Check in the manual that they are correct. (I say this to cover myself -
> you edit xorg.conf at your own risk).
>
> Once you have done that, add an extra line in the Monitor section:
> Modeline "1152x864"  144.00  1152 1216 1344 1600  864 865 868 900 +hsync
> +vsync
>
> This is exactly the output from xvidtine with Modeline added to the
> beginning (this is my example, yours will be different for 1024x768). Now
> alter the pixel clock to the number you calculated.
>
> Restart X, and now you should have a higher refresh rate.
>
> Why they can't provide high refresh rate modes with X I don't know.
>
> Hope that helps,
>
>
> Jonathan
>

thank You Jonathan

>
>
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