Changing the refresh rate in fedora 2

Hi all,
 I could not find refresh rate in Display settings.
 How can i change the refresh rate on Linux(Fedora Core 2)?

Thanks in advance.
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manish_regmiAsked:
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Karl Heinz KremerConnect With a Mentor Commented:
AFAIK FC2 does not give you direct access to the refresh rate. Make sure that you specify the properties of your monitor (e.g. valid ranges of horizontal and vertical rates), then use system-config-display to setup the resolution and color depth. This program is supposed to come up with the best settings - meaning the hightest possible refresh rate for a given setting. If this does not work, you can always modify the settings manually in /etc/X11/xorg.conf

This page http://www.tldp.org/HOWTO/text/XFree86-Video-Timings-HOWTO and this program/tool http://www.dkfz-heidelberg.de/spec/linux/modeline/index.html.en will help to do it manually.
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e-tsikCommented:
Hi :-)

Vertical refresh rate is one of the frequent pains i get from X, specifically when I try to use it with an old screen.

The easiest way to change the refresh rate I know is to edit the file
/etc/X11/xorg.conf

Look up the word: VertRefresh
Modify the higher value to you monitor's maximum vertical refresh rate.
These settings apply when you restart the X server (CTRL-ALT-BackSpace should do the trick)

(example)
Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Monitor Vendor"
        ModelName    "Sony CPD-100SX"
        DisplaySize  280        210
        HorizSync    30.0 - 65.0
        VertRefresh  50.0 - 120.0
        Option      "dpms"
EndSection

Another thing you can do while you're editing the file is to modify the maximum screen resolution. Look below in section "Screen" - you can modify the resolution modes there:
Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        Monitor    "Monitor0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1024x768" "800x600" "640x480"
        EndSubSection
EndSection

You can switch resolution modes with CTRL+ALT+Kepad+ and CTL+ALT+Keypad-

Enjoy!
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manish_regmiAuthor Commented:
Thanks for your input.

 But i want to make the refresh rate exactly 100HZ.
Like in windows we do from display properties.

Manish
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Karl Heinz KremerCommented:
This means that you have to deal with the modline configuration manually. Look into the HOWTO I linked to.
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e-tsikConnect With a Mentor Commented:
Well,

X already selects the highest vertical refresh it can match with the possible refresh rates it thinks the display card supports.

VertRefresh  100.0 - 100.0

Should do the trick, although it may also make your X server unusable because it wouldn't be able to find a suitable refresh rate matching X's own modes.

Windows has an excellent mode-switching system because all the drivers and monitors are designed to be used on Windows. To achieve the same on Linux, you would have to read the exact refresh-rate/modes your display card manufacturer supports and then match them with the refresh-rate/modes your screen supports.

You could also try
VertRefresh  98.0 - 102.0

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manish_regmiAuthor Commented:
Ok,
 Now, i have generated the modline from the link you gave

For 800x600 at 100HZ, it gives,

////////////////////////////////////////////////////

Horizontal Resolution:  800  
Vertical Resolution:  600  

   Vertical Refresh Rate:  100.00 Hz  
Horizontal Refresh Rate:  63.83 KHz  
Dot Clock Frequence:  68.94 MHz  



# V-freq: 100.00 Hz  // h-freq: 63.83 KHz
Modeline "800x600" 68.94   800  840  928 1080   600  600  602  638
 
/////////////////////////////////////////////////

Now should i change the "modes"(or tell me which line to change) line in x.org to above value(Modeline "800x600" 68.94   800  840  928 1080   600  600  602  638 ).
But will it harm? I am sure it(800x600 at 100HZ) works in windows.

Manish
 
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manish_regmiAuthor Commented:
hi e-tsik,
 I will try that and return tomorrow.

Thanks
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Karl Heinz KremerCommented:
If you already have a modline for 800x600 in your config file, just comment out the existing line and add the new one right after the original one (which now is commented out). Give it a try. A multi-sync monitor should not get damaged by this. Don't do something like this with fixed frequency monitors!
If it does not work, you can alwasy stop X by using Ctrl-Alt-backspace
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manish_regmiAuthor Commented:
hi khkremer and e-tsk,
 I will try the suggestions and return tomorrow.

Thanks
Manish
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manish_regmiAuthor Commented:
hi khkremer and e-tsk,
 Both of your suggestions worked. But e-tsk's idea does not work for all values as he said.

Thanks for your help
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