I'm using Ubuntu 16.04 installed on Lenovo ThinkPad T500 laptop with two external monitors connected via display and VGA ports.

I think the issue started after I upgraded to Ubuntu 16.04. But I'm not sure about this.

Occasionally at some random moment one of the monitors turns off. It looks like there is no signal on the monitor. In 2-5 seconds the monitor turns on. This might happen several times in a row with small delays or might not happen for a long time. Both monitors might turn off at the same time or one by one.

I do not understand why this happens. Either I do not understand what should I do to reproduce the issue. Last time (a moment before I wrote this) this happened when I switch to a different tab in Google Chrome and pause YouTube music video. But when I try to do the same one more time the issue is not reproduced. I kept using the computer all the time looking at the screen and writing this question at the moment when issue happened

I failed to find any signs of the issue in the logs.

My issue looks close to Monitor turning off randomly Ubuntu 13.10 with the differences that only one monitor might turn off instead of two and they turn on automatically.

By coincidence I've entered the command xset -q and pressed enter key right at the moment when the monitor turned off. I waited for several seconds and saw the result

$ xset -q
Keyboard Control:
  auto repeat:  on    key click percent:  0    LED mask:  00000000
  XKB indicators:
    00: Caps Lock:   off    01: Num Lock:    off    02: Scroll Lock: off
    03: Compose:     off    04: Kana:        off    05: Sleep:       off
    06: Suspend:     off    07: Mute:        off    08: Misc:        off
    09: Mail:        off    10: Charging:    off    11: Shift Lock:  off
    12: Group 2:     off    13: Mouse Keys:  off
  auto repeat delay:  500    repeat rate:  33
  auto repeating keys:  00ffffffdffffbbf
  bell percent:  50    bell pitch:  400    bell duration:  100
Pointer Control:
  acceleration:  5/1    threshold:  5
Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  0    cycle:  0
  default colormap:  0x22    BlackPixel:  0x0    WhitePixel:  0xffffff
Font Path:
DPMS (Energy Star):
  Standby: 0    Suspend: 0    Off: 0
  DPMS is Enabled
  Monitor is On

What can I do to investigate the issue? What log files should I check? I failed to find any signs of the issue anywhere in the system.

Is this a known issue? I might describe it wrong when searching for it and thus failed to find it.

How can I understand if it is a hardware or software issue? I might install Windows and see if the issue happens with Windows or not. But may be there might be an option to check this using Ubuntu.

What can I do to prevent the issue?


Following suggestion in the answer I tried to do the following to reduce the refresh rate on my screens. I had a refresh rate 59.95 Hz and decided to change it to 58 Hz.

Identify existing refresh rate

xrandr -q

Created parameters for the new mode

$ cvt 1920 1200 58

\# 1920x1200 57.93 Hz (CVT) hsync: 72.01 kHz; pclk: 185.50 MHz
Modeline "1920x1200_58.00"  185.50  1920 2048 2248 2576  1200 1203 1209 1243 -hsync +vsync

Registered new mode

$ xrandr --newmode "1920x1200_58.00"  185.50  1920 2048 2248 2576  1200 1203 1209 1243 -hsync +vsync

Added this new mode to both screens

$ xrandr --addmode DP1 1920x1200_58.00
$ xrandr --addmode DP2 1920x1200_58.00

Selected this newly added mode for both screens

$ xrandr --output DP1 --mode 1920x1200_58.00
$ xrandr --output DP2 --mode 1920x1200_58.00

As a result now xrandr -q shows the following output

$ xrandr --query
Screen 0: minimum 8 x 8, current 3840 x 1248, maximum 32767 x 32767
eDP1 connected (normal left inverted right x axis y axis)
   1920x1080     60.00 +  59.93  
   1680x1050     59.95    59.88  
   1600x1024     60.17  
   1400x1050     59.98  
   1600x900      60.00  
   1280x1024     60.02  
   1440x900      59.89  
   1280x960      60.00  
   1368x768      60.00  
   1360x768      59.80    59.96  
   1152x864      60.00  
   1280x720      60.00  
   1024x768      60.00  
   1024x576      60.00  
   960x540       60.00  
   800x600       60.32    56.25  
   864x486       60.00  
   640x480       59.94  
   720x405       60.00  
   640x360       60.00  
DP1 connected 1920x1200+0+48 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95 +
   1920x1080     60.00  
   1600x1200     60.00  
   1680x1050     59.95  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       60.00  
   720x400       70.08  
   1920x1200_58.00  57.93* 
DP2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95 +
   1920x1080     60.00  
   1600x1200     60.00  
   1680x1050     59.95  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       60.00  
   720x400       70.08  
   1920x1200_58.00  57.93* 
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

I'm checking if the issue repeats or not now. If it does not this means that I've got the solution and I'll mark it as answer.

I still do not know how to permanently store these settings, I guess I should add a new file to the /usr/share/X11/xorg.conf.d folder following recommendations in this document. I'm going to study this when I see that the issue is fixed.

  • 1
    wow! I was facing this same issue with my HP laptop and my viewsonic external display on Ubuntu 16.04, and the fact that your question turned into an answer giving exact details was really helpful. I wouldn't probably have had the guts to delve through addmode, output etc without the exact details that were provided by you! Thanks! Mar 25, 2019 at 8:16
  • Unfortunately I run into a BadMatch when trying to addmode to my monitor, and debugging this stuff is incredibly frustrating.
    – mkobit
    Jun 27, 2019 at 16:41
  • Dell laptop with Intel i915 reporting in: I had this for the last five years on 16.04 and on 20.04., even when only the external HDMI monitor is enabled. Only that it happens once in 3-4 days. Now I start the experiment with 59.94 FPS instead of 60.
    – Levente
    Feb 6, 2021 at 23:14

5 Answers 5


If your screen is switching off it might be struggling to keep sync with the output signal.

There are two main reasons for this , the first is refresh rates being too high for the screen to keep up with and the second is the cables are not good enough. There is an outside chance your graphics card can't cope with multiple screens but most are powerful enough.

Which connection method are you using and what resolution are the screens set to ?

Xrandr will allow you set and query the refresh rates. Sometimes knocking a few hz off the frequency can work around bad cables.

If you have other cables you can borrow try them.

you xorg logs (in /var/log/ but check the dates of the files) should show the resync attempts and shed some light as well

  • 1
    I've tried to apply your recommendation to lower the refresh rate and updated the question. If everything goes well I think this should be the accepted answer and my problem should be fixed. Thank you for your help! May 17, 2016 at 11:24
  • the archlinux guide should suffice , just add the modeline to your xorg and or limit the refreshes your monitor is allowed to use. if that doesn't work its possible that your monitors might have a broken or flakey EDID which is confusing your graphics card , you can force x to use a stored EDID from a file instead of querying it from the monitor each time and possibly getting bad results. might also be worth making the built in screen go at that ever so slightly slower refresh to make less work for the graphics card.
    – Amias
    May 17, 2016 at 12:07
  • 3
    Looks like monitor do not turn off randomly now after I've changed refresh rate. I'll check it for several more days and update the question when done. Thank you for your help! May 17, 2016 at 12:53
  • 1
    yay ! <happydance>
    – Amias
    May 17, 2016 at 16:28
  • Thanks for the pointer on cable quality. I think my VGA cable is not that good. I had perfect display quality for past 6 months, then suddenly this issue keeps popping up! Here's a good article on how to check whether quality of the VGA cable is good or not... Some cheap cables don't have all pins connected through and through. techwalla.com/articles/… Mar 25, 2019 at 8:20

The same has been happening to me intermittently over several months. I use Ubuntu 16.04 and have a Dell Latitude-E7440. There seems to be a pattern here with laptops! Mine seems to be due to the battery not charing properly and the Energy settings getting changed some how. I ran this to turn the Energy features off.

$ ~ xset -dpms

This resolved my screen turning off randomly.

  • I tried out the xset -dpms command, but in my particular case, it didn't solve the issue. Thanks anyway! Mar 25, 2019 at 8:17

I had this exact same issue on lenovo thinkpad E550 notebook.

  • one monitor turned off at random moment

  • after few seconds it turned itself back on

  • it was happening only to monitor connected via VGA

  • it was happening only when notebook was on adapter (this took me a looong time to figure out)

It turned out that there was a firmware issue on significant number of thinkpad notebooks, fortunately a firmware upgrade was released.

Unfortunately upgrade can be only performed on Windows (I had dual boot). Instructions here

In case the link dies, you have to download this zip file and follow the instructions in the manual inside the zip.


I had the same issue with Kubuntu 20.04 and a two monitor setup powered by a cheap Intel UHD Graphics 600 mini-PC.

I tried all the given solutions here and none worked. What we discovered was that when we unplugged one of the two monitors, the problem went away. We figure the cheap design of this low-cost mini-PC was to blame--it couldn't drive 2 monitors at once reliably.


Ok, This may sounds crazy, but that is what I had: If you laptop is near some electric equipment, it may cause this malfunction. In my case I another laptop under this one and he was the one probably causing magnetic interferences. I checked it numerous times to be sure.

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