Validating Vertical Screen Refresh Rate

Woodsman · 05-03-2008, 08:44 PM

How do I do this?

KDE reports a screen refresh rate, but nowhere else can I find this information to validate what KDE reports. I ask because when I use the nv drivers, KDE reports 75 Hz and when I use the proprietary nvidia driver, KDE reports 50 Hz. This latter number bothers me because the monitor only supports 56 to 75 Hz. That range is explicitly defined in my xorg.conf. Therefore either the nvidia drivers are ignoring this directive or KDE is incorrect.

I don't know whether the values reported are correct and I'd like a second or third method to determine the frequency.

Edit: I'm using Slackware 12.1, KDE 3.5.9, kernel 2.6.24.5, nvidia drivers 169.09. Motherboard is Asus M2NPV-VM with built-in video chip (nForce 430/MCP51). Monitor is a 17" Samsung SyncMaster 712N LCD, native resolution is 1280x1024.

IsaacKuo · 05-03-2008, 09:44 PM

My experience is that the nvidia official driver does indeed ignore what you set in xorg.conf, unless you use a "strange" custom modeline name. For example, if you use a resolution named "1280x960", it doesn't matter even if you specify a custom Modeline. The nvidia driver will ignore your custom Modeline and it will ignore your VertRefresh option. But if you use a resolution named "1280x960foobar", it will accept your custom modeline.

Smedley · 05-03-2008, 10:07 PM

Quote:

Originally Posted by Woodsman

How do I do this?

KDE reports a screen refresh rate, but nowhere else can I find this information to validate what KDE reports. I ask because when I use the nv drivers, KDE reports 75 Hz and when I use the proprietary nvidia driver, KDE reports 50 Hz. This latter number bothers me because the monitor only supports 56 to 75 Hz. That range is explicitly defined in my xorg.conf. Therefore either the nvidia drivers are ignoring this directive or KDE is incorrect.

I don't know whether the values reported are correct and I'd like a second or third method to determine the frequency.

Edit: I'm using Slackware 12.1, KDE 3.5.9, kernel 2.6.24.5, nvidia drivers 169.09. Motherboard is Asus M2NPV-VM with built-in video chip (nForce 430/MCP51). Monitor is a 17" Samsung SyncMaster 712N LCD, native resolution is 1280x1024.

On a side note, there are known issues with your kernel and the nVidia drivers. Check out the nvnews forums.

Franklin · 05-03-2008, 10:48 PM

All the monitors I have used have on screen utilities for brightness, contrast, etc.
One of these is usually a display of the current resolution and refresh rate. If this is available, I would believe what that tells me over anything else.

mRgOBLIN · 05-03-2008, 10:53 PM

Try running the "nvidia-settings" application see what it reports.

Woodsman · 05-04-2008, 02:30 PM

Quote:

My experience is that the nvidia official driver does indeed ignore what you set in xorg.conf

I'll keep that in mind. This is my first box with the nvidia drivers.

Quote:

My experience is that the nvidia official driver does indeed ignore what you set in xorg.conf

Possibly. However, the problem existed in Slackware 12.0 (kernel 2.6.21.5) too.

Quote:

All the monitors I have used have on screen utilities for brightness, contrast, etc. One of these is usually a display of the current resolution and refresh rate. If this is available, I would believe what that tells me over anything else.

I would love to learn how to access those controls on my monitor. The manual that came with the monitor is awful (I have no other complaints about the monitor). I'm sure there is a secret combination to make the buttons display the information you describe, but I have not found that secret. The menu button does nothing on my monitor. I would like to adjust the contract.

Quote:

Try running the "nvidia-settings" application see what it reports.

I did that and the refresh rate is reported as 75 Hz.

I also tried xvidtune, which reported 75 Hz.

The problem seems to be xrandr. The KDE Control Center extracts information through krandrtray, which is a front-end to xrandr. When I run xrandr --query I see the same weird frequency results as in KDE. xrandr reports only 50 and 53 Hz for 1280 x 1024 display.

Can anybody else verify that xrandr is incorrectly displaying the refresh rate? Or offer troubleshooting tips why xrandr reports what I see?

Franklin · 05-04-2008, 03:19 PM

Does your model come with six buttons on the bottom right side of the monitor?

If so, the button all the way on the right when pushed may give you that info.

1. Picture Brightness Contrast
2. Color Color Tone Color Control Gamma
3. Image Coarse Fine Sharpness H-Position V-Position
4. OSD Language H-Position V-Position Transparency Display Time
5. Setup Image Reset Color Reset
6. Information

Code:

steve@sundog:~$ xrandr
Screen 0: minimum 320 x 200, current 1440 x 900, maximum 1440 x 1440
VGA connected 1440x900+0+0 (normal left inverted right x axis y axis) 408mm x 255mm
   1440x900       59.9*+   75.0
   1280x1024      75.0     59.9
   1440x900@75.0   75.0
   1280x960       59.9
   1152x864       75.0     74.8
   1024x768       75.1     70.1     60.0
   832x624        74.6
   800x600        75.0     60.3     56.2
   640x480        75.0     60.0
   720x400        70.1
steve@sundog:~$

xrander states 59.9, my monitor states 60Hz

I'm using intel (not nvidia - sorry) graphics (intel i915) LG Flatron Wide LCD

HTH

digger95 · 05-04-2008, 04:04 PM

Mine seems to be okay woodsman.

Xrandr reports 85Hz and my monitor reports 87Hz:

Code:

slacker[~]$ xrandr
Screen 0: minimum 640 x 480, current 1024 x 768, maximum 1280 x 1024
default connected 1024x768+0+0 (normal left inverted right) 0mm x 0mm
   1024x768       85.0* 
   1280x1024      60.0     85.0  
   800x600        85.0  
   640x480        85.0

speck · 05-04-2008, 04:10 PM

xrandr is incorrect for me as well. My monitor (19in 1280x1024 LCD) display screen reports 60 (which is correct), not 50.

Code:

xrandr
Screen 0: minimum 320 x 240, current 1280 x 1024, maximum 1280 x 1024
default connected 1280x1024+0+0 0mm x 0mm
   1280x1024      50.0* 
   1024x768       51.0     56.0  
   800x600        52.0     57.0     58.0     59.0     60.0  
   640x480        53.0     63.0  
   1280x960       54.0  
   1152x768       55.0  
   800x512        61.0  
   640x512        62.0  
   576x384        64.0  
   512x384        65.0     66.0  
   400x300        67.0     68.0     69.0  
   320x240        70.0

digger95 · 05-04-2008, 04:16 PM

I was just perusing the manual for your monitor:

712N User Manual

You're right, it's a bit hard to follow, but you should definitely be able to access your monitor's current refresh rate, etc. I'm just not very good with manuals I'm afraid. Perhaps someone more literate than I can help.

Dig

T3slider · 05-04-2008, 04:42 PM

I'm still on Slackware 12.0 and xrandr reports 50...

Code:

t3slider@linux:~$ xrandr
Screen 0: minimum 320 x 240, current 1680 x 1050, maximum 1680 x 1050
default connected 1680x1050+0+0 0mm x 0mm
   1680x1050      50.0*    55.0
   1280x1024      51.0     61.0
   1024x768       52.0     65.0     66.0
   800x600        53.0     69.0     70.0     71.0     72.0     73.0
   640x480        54.0     77.0     78.0     79.0
   1600x1024      56.0
   1440x900       57.0     58.0
   1400x1050      59.0     60.0
   1280x960       62.0
   1280x720       63.0
   1152x864       64.0
   832x624        67.0     68.0
   800x512        74.0
   640x512        75.0     76.0
   576x432        80.0
   512x384        81.0     82.0     83.0
   416x312        84.0
   400x300        85.0     86.0     87.0     88.0
   320x240        89.0     90.0     91.0

...while nVidia settings reports 59.95 Hz (and my monitor reports 60 Hz). KDE reports 50 Hz as well (but it probably gets its info from xrandr). It appears that there is (and has been for a while) a bug in xrandr that *may* falsely report the refresh rate. I would trust the proprietary nVidia driver's settings tool over any run-of-the-mill KDE tool, but I could be wrong.

Woodsman · 05-04-2008, 05:31 PM

Quote:

You're right, it's a bit hard to follow, but you should definitely be able to access your monitor's current refresh rate, etc. I'm just not very good with manuals I'm afraid. Perhaps someone more literate than I can help.

Funny --- about an hour after posting, I got fed up and started exercising the hell out of the menu button. Eventually the menu appeared.

Eventually I figured out how to navigate the menu and yes, like all those blinking clocks on VCR and DVD players, there is a reason why hardware engineers receive the criticisms they do. I just hate anything that is designed to be multi purpose using only a few buttons. A nightmare!

Anyway, eventually I got to the information menu option and confirmed my monitor was running at 75 Hz.

Quote:

It appears that there is (and has been for a while) a bug in xrandr that *may* falsely report the refresh rate.

So xrandr remains suspect, at least here on my installation. Based upon my monitor specs, I expect the two numbers from xrandr to be 60 Hz and 75 Hz, not 50 and 53.

Quote:

xrandr is incorrect for me as well. My monitor (19in 1280x1024 LCD) display screen reports 60 (which is correct), not 50.

I wonder whether there is a calculation error/bug in the source code for 1280x1024 displays?

T3slider · 05-04-2008, 05:50 PM

Quote:

Originally Posted by Woodsman

I wonder whether there is a calculation error/bug in the source code for 1280x1024 displays?

Or maybe 1280x1024 and above, since I have the same (harmless) issue with a 1680x1050 display (though Franklin has a 1440x900 display, from the looks of it, and it is accurate).

Franklin · 05-04-2008, 06:07 PM

Quote:

Originally Posted by T3slider

Or maybe 1280x1024 and above, since I have the same (harmless) issue with a 1680x1050 display (though Franklin has a 1440x900 display, from the looks of it, and it is accurate).

But I'm not using nVidia.

Back when I was (the good ol' days) I remember an option that I had to use in xorg.conf to make certain that the monitor info was not polled. This needed to be done so that I could use the DisplaySize option to set a custom DPI for my fonts. I'm curious whether either of you with bogus xrandr data are using that or a similar option that might be giving you incorrect readings.

Just a random thot.

ErV · 05-04-2008, 06:21 PM

Quote:

Originally Posted by Woodsman

How do I do this?

On newer/better monitors refresh rate should be visible in on-screen menu (monitor's menu).
You can also launch nvidia-settings and check refresh rate (since this is known NVidia problem).
You can also check refresh rate visually - I simply can't look at 60 Hz and below for a long time, so you'll clearly see the difference between 75Hz and 50HZ.
Also, if CRT monitor is not "smart", and you'll try to use values above/below supported it should go out of sync (horizontal/vertical synchronization), which will be clearly visible. If this doesn't happen, this means that refresh rate is near or inside supported range. Can't gurantee this, though...