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tramni1980 08-11-2006 03:43 AM

X11-set the vertical refresh rate
hello. I am running Slackware Linux 10.2 and kernel 2.4.31
I have Dell Trinitron UltraScan P991 monitor. Its specifications say its horizontal refresh rate is 30-107 kHz and its vertical refresh rate is 48-120 Hz. I have entered these values in xorg.conf and I have set the default resolution to 1024x768. Now my monitor s working at vertical refresh rate of 85 Hz. Is there some way to set the vertical refresh rate at some higher value? Under Windows I set it at 120 Hz and a similar resilution. I would be glad if I set the vertical refresh rate at 100 Hz and resolution of 1024x768.

Old_Fogie 08-11-2006 04:06 AM

you need to make sure you put in your refreshes correctly and with the zero's too for starters just in case you didnt have them.

you may ? want to use a "modeline" to force it once you made sure you have your refreshes put in correctly.

in terminal for a "100" vrefresh you would type for example:


gtf 1024 768 100 -x
which would give you an output something like this (mine gave me this, yours couldvary)


# 1024x768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHz
Modeline "1024x768_100.00" 113.31 1024 1096 1208 1392 768 769 772 814 -HSync +Vsync
then you just put that in your monitor section of your /etc/X11/xorg.conf and then restart the X server.

be sure to back up your xorg just in case.

but to be honest 85 is really nice, even for games. most online games limit FPS to 60. just thought I'd mention that.

jschiwal 08-11-2006 04:15 AM

You could try your own modeline.
Enter the command "gtf 1024 786 100 -x5

Remove the trailing ".00" from the name "1024x786_100.00" -> "1024x786_100".

If your xorg.conf file is the type with a modeline section, then place the modeline there, and add "1024x786_100" to the Screen section's modes. For example, emphasized the lines that I used to get 1280x800 resolution on my laptop.

Section "Modes"
  Identifier  "Modes[0]"

  # 1280x800 @ 56.00 Hz (GTF) hsync: 46.26 kHz; pclk: 77.71 MHz
  Modeline "1280x800_56"  77.71  1280 1344 1480 1680  800 801 804 826  -HSync +Vsync

  Modeline      "1024x600" 56.35 1024 1072 1176 1328 600 601 604 624
  Modeline      "1024x600" 55.52 1024 1072 1176 1328 600 601 604 624
  Modeline      "1024x768" 65.00 1024 1048 1184 1344 768 771 777 806

Section "Screen"
  DefaultDepth 24
  SubSection "Display"
    Depth      15
    Modes      "1280x800_56" "1024x768" "1024x600" "800x600" "768x576" "640x480"
  SubSection "Display"
    Depth      16
    Modes      "1280x8y00_56" "1024x768" "1024x600" "800x600" "768x576" "640x480"

If your xorg.conf file doesn't have a modelines section, then you can add your new modeline to the Monitor section instead. You will still need to edit the Modes entries.

Good Luck.

tramni1980 08-11-2006 05:20 AM

I did what you told me. I ran "gtf 1024 768 100 -x". The output was:

# 1024x768 @ 100.00 Hz (GTF) hsync: 81.40 kHz; pclk: 113.31 MHz
Modeline "1024x768_100.00" 113.31 1024 1096 1208 1392 768 769 772 814 -HSync +Vsync
I added this to the end of my "Monitor" section in xorg.conf. When I restarted X11 the vertical refresh rate was as I wished-101Hz. But What I found out is that when I open an application, for example a web browser of Kate or whatever, the right edge of the application's window is somewhat "clipped" - I do not see the scrollbar, the "x" button at the upper-right end. I do not see the rigt panel-hiding button. It looks like the desktop has "expanded" but I do not see all of it on the screen. Do you have any idea what it is, any remedy?

tramni1980 08-11-2006 05:34 AM

To be able to see the "x" buuton that closes an application, I have to move the window to the left with the mouse. Just then the "x" buuton and the scroll bar appear.

tramni1980 08-11-2006 05:45 AM

Oh, I solved that problem myself:) I just had to tune the monitor itself with its buttons. Thank you very much indeed :). Now everything seems to be all right. The only thing that puzzles me is that when I go to the "Configure Desktop"->"Display" menu, it says that the refresh rate is 101 hz, and when I press the button on my monitor it says that it is working at 104 Hz. What is that discrepancy due to?

Old_Fogie 08-11-2006 12:09 PM

Hi Tramni

I don't know why that happens at times to be honest.

I have one pc, that I just leave at the default 60 hz refresh rate that slackware gives, because it is an old monitor and old pc, and it reports 61 Hz. I've got another that reports 59.

So I really don't know. I remember in windows, when I used special refresh rates, for example, that there was a check box to "display unsupported resolutions".

Maybe you should verify the vertical refresh modes that your monitor and yo

Old_Fogie 08-11-2006 12:11 PM

oops this goes witht the above opera messing up on me

video card support.

then just subsitute that value into your modeline in console then your xorg file accordingly.

cwwilson721 08-11-2006 12:16 PM

lol. One of many reasons why I don't use Opera...

tramni1980 08-11-2006 12:23 PM

I see. There is no trouble I thing in leaving things as they are now? The monitor really works at a refresh rate of about 100Hz and everything is pretty good. Is there any potential problem arising out of that?

tramni1980 08-11-2006 12:46 PM

Old Fogie, there was probably a problem with the message you last posted, it looks like that:
oops this goes witht the above opera messing up on me

video card support.

then just subsitute that value into your modeline in console then your xorg file accordingly.

Probably there are some rows missing?

Old_Fogie 08-11-2006 01:49 PM

for some reason it posted my message on me, dont know what happened there.

what I meant was for you just to verify from the documentation that you have for your monitor and video card that it's ok for you to use the 1024x768 resolution at 100 Hz.

chances are your fine if the equipment is newer, say last 2 years or so, but it's allways a good chance to check.

i just threw out 100 hz to you as an example really.

regarding opera: yea, it's glitchy but I have to use it on my old laptop.

it's 300 mhz and all my usual web pages fly on this as if I'm using a new pc :D

but some pages dont render at all, like yahoo news.

but it takes about 40 seconds for firefox to load, it's just unusable on my old hardware.

if there was no opera this laptop would be unusable in linux unfortunately, the mozilla's family browsers are too bogged down under 600mhz pc's :(

tramni1980 08-11-2006 04:05 PM

My videocard is Intel(R) 82845G Graphics Controller. I couldn't find any relevant info in the internet abot whether it supports 1024x768 at 100Hz. Concerning the monitor, its documentation says teh following:
Horizontal scan range: 30 kHz to 107 kHz (automatic)

Vertical scan range: 48 Hz to 120 Hz (automatic)

Optimal preset resolution: 1024 x 768 or 1280 x 1024 at 85 Hz

Highest preset resolution: 1600 x 1200 at 85 Hz

I am currently using it at 1024x768 at about 100Hz. In windows I have set it to work at 120 Hz. However, it seems to me that it is not too healthy for it to work at such high frequencies. I hope that the current configuration is as well ok. What do you think?

Old_Fogie 08-11-2006 05:01 PM

well, according to what you posted


Optimal preset resolution: 1024 x 768 or 1280 x 1024 at 85 Hz
looks like you should really go back to 85 refresh rate to be honest.

no point in over syncing your monitor

tramni1980 08-12-2006 08:54 AM

ok,thank you very much indeed :)it was quite a helpful discussion :)
My next problem is installing the webcam and the UPS software, but I do not have any idea in which forum to post. My webcam install thread has sat in this forum for several days now with no answer. Would you suggest me in which forum to post it :)

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