Refresh rate problems in Ubuntu Linux

Hi guys,

I'm still messing around with linux, trying to get my system running. I seem to have everything in check so far, except my resolution is 1280 x 1024 and the refresh rate 'seems' to be set at 85. I have the same resolution in Windows, but when I boot into linux it seems to flicker much more.

Any help would be great.

If it's flickering it's probably not running at 85hz. It may be that Ubuntu misdetected your screen's scanrates. Check in /etc/X11/xorg for a section that looks something like this:

Section "Monitor"
Identifier "DELL1"
Option "DPMS"
HorizSync 31-83
VertRefresh 56-76
EndSection

The HorizSync and VertRefresh should be in your screen's manual or printed on the back, or you should be able to find it onine. The ones I have is for a 1280x1024 LCD, so they won't help you much. You're probably looking for something like 30-75 and 50-160 or something in that area. I'm assuming you're working with a CRT.

Thank you for the response, excuse my ignorance, but how would I go about accessing '/etc/X11/xorg' ? I'm completely new to linux.

Thanks again

open a terminal/console and type:

less /etc/X11/xorg.conf

I just want you to see it, not to edit it. Ubuntu has good graphical tools to fix these sort of problems. I'm just not familiar with them to be able to direct you, but at least it helps to know where the problem is.

To get out of less press 'q'

Hi koffie, this is what I find:


Section "Screen"
Identifier "Default Screen"
Device "Generic Video Card"
Monitor "DELL M991"
DefaultDepth 24
SubSection "Display"
Depth 1
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection

This is the wrong section - send me the section that contains a line similar to:

Identifier "DELL M991"

Or post the whole file

You can also run run xvidtune from an xterm to confirm the resolution and vertical/horizontal refresh rates. If this is for a CRT, give us the size of the screen so we can suggest some refresh rates.

First open a Gnome terminal or xterm. You need to be root, IIRC in Ubuntu it's "sudo su" or "su". There's probably a gnome-sudo GUI there for doing root admin tasks. If you need to edit the xorg.conf just use gedit as root.

There's most likely some kind of GUI tool for configuring the refresh rates, maybe it's best to look for that first. I'm not an Ubuntu user and I hardly ever use the GUI tools to do this stuff.

This is the entire file:

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf(5) manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/share/fonts/X11/cyrillic"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/Type1"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
# path to defoma fonts
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
Load "i2c"
Load "bitmap"
Load "ddc"
Load "dri"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "vbe"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
Option "Device" "/dev/input/mice"
Option "Protocol" "ImPS/2"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "true"
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "stylus"
Option "Device" "/dev/input/wacom"
Option "Type" "stylus"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "eraser"
Option "Device" "/dev/input/wacom"
Option "Type" "eraser"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
Driver "wacom"
Identifier "cursor"
Option "Device" "/dev/input/wacom"
Option "Type" "cursor"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "Device"
Identifier "Generic Video Card"
Driver "vesa"
BusID "PCI:1:0:0"
EndSection

Section "Monitor"
Identifier "DELL M991"
Option "DPMS"
EndSection

Section "Screen"
Identifier "Default Screen"
Device "Generic Video Card"
Monitor "DELL M991"
DefaultDepth 24
SubSection "Display"
Depth 1
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
InputDevice "Generic Keyboard"
InputDevice "Configured Mouse"
InputDevice "stylus" "SendCoreEvents"
InputDevice "cursor" "SendCoreEvents"
InputDevice "eraser" "SendCoreEvents"
EndSection

Section "DRI"
Mode 0666
EndSection

There is a GUI tool to change the refresh rate. It says the refresh rate is 85. It's a 19" Dell Monitor.

What type of graphics card do you use. If you use a Nvidia Card or ATI card I suggest installing the drivers for them. If it's an nvidia card, install the drivers, and run nvidia-settings from a commandline. nvidia-settings will sort you out if that is the case. But in regard to above, you have no refresh rate set on your xorg.conf, so it will run at the default 60Hz, even though I don't know where that tool gets it's 85 from!

HTH

This is probably the problem:

Section "Monitor"
Identifier "DELL M991"
Option "DPMS"
EndSection

No scanrates defined. Here's what you can try.

1. log out, so you have the login screen in front of you.

2. Hit Ctrl+Alt+F1 - this will dump you into a console. Login as your normal user.

3. Stop the X server:


4. Backup your X config:


5. Edit that file:


Change that section to:


Save it, exit the editor. I got the scanrates here.

6. Start the gui again:


If it blows up, repeat the same process to revert the file, but change step 5 to:

Ooh, Graviti is right. Here's the problem:

Section "Device"
Identifier "Generic Video Card"
Driver "vesa"
BusID "PCI:1:0:0"
EndSection

vesa can only do 1024x768@60Hz - you need the correct video driver for your card.

Do:


and let us know the output.

did it work? did it work?

This system uses a "VIA/S3G UniChrome Pro IGP" onboard display card.

Could I possibly force a refresh rate by adding a line to that file?

Oh I didnt see all these replies. Let me try and fiddle.

Velenoso said:

This system uses a "VIA/S3G UniChrome Pro IGP" onboard display card.

Click to expand...

In that case you need


instead of


Could I possibly force a refresh rate by adding a line to that file?[/QUOTE]

It's possible, but having done it, I wouldn't recommend it. If you get it wrong you can break your monitor.

Should I just try that last bit then?

Change:

Section "Device"
Identifier "Generic Video Card"
Driver "vesa"
BusID "PCI:1:0:0"
EndSection

To:

Section "Device"
Identifier "Generic Video Card"
Driver "via"
BusID "PCI:1:0:0"
EndSection

?

Just keep in mind that trying to force a too high refresh rate on a monitor incapable of handling it will either :

- have the monitor switch itself off
- burst out in flames or damage itself

As it's running @ 85Hz in Windows without any problems, then it should also be fine with Linux.

The_Librarian said:

Just keep in mind that trying to force a too high refresh rate on a monitor incapable of handling it will either :

- have the monitor switch itself off
- burst out in flames or damage itself

As it's running @ 85Hz in Windows without any problems, then it should also be fine with Linux.

Click to expand...

Which is why I suggested adding the correct HorizSync and VertRefresh (not to be confused with the refreshrate). xorg uses these to calculate the best refreshrate.

koffiejunkie said:

Which is why I suggested adding the correct HorizSync and VertRefresh (not to be confused with the refreshrate). xorg uses these to calculate the best refreshrate.

Click to expand...

Good thinking that.

Thanks guys, Im going to try this now. Just takes long because I have to boot into windows to access this forum. Have not set up internet on linux yet...