66

My eyes hurt so I thought I should check the screen refresh rate (monitor frequency), but I couldn't find it.

Where is it? (in Ubuntu 12)

Pandya
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HappyDeveloper
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    If your eyes hurt, I suggest you check out the topic of color temperature correction (F.lux and redshift are two great apps for this) – Bernát Jun 10 '15 at 19:02
  • For me Unity seems to be the problem. I have an HDMI Y connector (two inputs, one output, you can choose which one to pass through), which I confirmed by a few tests: 1) I plugged another computer with the same driver/OS into the same thing and it flickered. 2) I lowered the resolution and it reduced the flicker but didn't remove it 3) I plugged my computer into the same thing with a USB-C to HDMI cable and it continued flickering 4) I plugged my computer directly with the USB-C to HDMI cable into the monitor and it continued flickering, although slightly reduced. 5) Mirroring doesn't flicker. – Lampe2020 Oct 08 '23 at 20:09

2 Answers2

80

Compiz looked like it worked. But it didn't work.

So the solution to this is the following.

First we check available modes.
$ xrandr
1440x900       59.9+*   75.0
1280x1024      75.0     60.0

Then we pick the mode, including resolution and refresh rate.
$ xrandr -s 1440x900 -r 75

Or just the refresh rate
$ xrandr -r 75

Let's see if it worked
$ xrandr
1440x900       59.9+    75.0*
1280x1024      75.0     60.0

Alright. Then all you have to do is add the command to Startup Applications and be done.

HappyDeveloper
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    I wonder why didnt some one mention this ?????? Rate 75.0 Hz not available for this size" . Its not the correct solution at all. – Pratik Joshi Feb 13 '15 at 18:21
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    @PratikCJoshi Try using a different type of cable, for example HDMI. – Niel de Wet Apr 13 '16 at 13:30
  • @PratikCJoshi You probably used xrandr -r 75.0, which may not work, while xrand -r 75 should. Even if the displayed framerate is something like 74.98 (my case) you should take the nominal value and use xrandr -r 75. – fsanches Oct 20 '16 at 02:14
  • Could somebody please tell me why GUI tools ignore refresh rate? If xrandr can do it, why can't they? Isn't it it a basic setting? – Nandakumar Edamana Jan 28 '17 at 16:11
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    BTW, from here: star (*) is the current mode, the plus (+) is the preferred one. Most monitors report a preferred mode to the driver. – Pablo Bianchi Apr 30 '17 at 22:19
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    I recently needed to use the xrandr command as follows: xrandr --output eDP-1 --mode 1920x1080 --rate 59.93 for this to work, otherwise there was no change. Check the output device from the 2nd line of xrandr output. Would be nice if there was a way without adjusting xorg.conf or adding a startup script to make this permanent. Somehow 60.01 (= the default rate) makes my eyes bleed (screen flickers in the dark areas), whilst using 59.93 doesn't (recent HP Probook). – 4levels Jun 22 '18 at 23:59
  • @4levels That worked. Here is an answer with that solution. – Alexis Wilke Feb 03 '21 at 19:16
16

open your terminal and type this 

sudo apt-get install compizconfig-settings-manager

then type compiz in your unity dash , it will list you compiz settings manager .Open compiz and at general options click at composite and there you have untick the detect refresh rate then you can manually set the value you want . enter image description here .

and two know allowed refresh rates for the resolution you can use xrandr

the second row are allowed refresh rates with respect to the resolutions . so by depending on resolutions you have set , you can change the refresh rate by using the above methods . enter image description here

Raja G
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