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I have never used a secondary display with Ubuntu before.

For the record, my hardware is Acer Predator Helios 300 laptop. Here is the About page in settings

enter image description here

I have a Dell 27" external monitor that I am connecting with a HDMI cable.

Here's how my settings screen looks like

enter image description here

So, it seems that the system is detecting the monitor, but my monitor says it does not read any signal from HDMI and goes to sleep after a few minutes.

As I was not the first person to come across this problem, my search turned out several of the previous questions.

  • From this question , I figured out I needed to install nvidia drivers, and so I did following this guide . (Not sure how I lived without this before. My video resolution is much better now)
  • From this question and this question , I realized I could use xrandr to troubleshoot the display, so, I installed it.

Here's some related outputs from this

xrandr | grep connected

eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 382mm x 215mm
DP-1-0 disconnected
DP-1-1 disconnected
HDMI-1-0 connected 1920x1080+0+0 600mm x 340mm

and

xrandr | grep "*"

   1920x1080    144.03*+  60.02    60.01    59.97    59.96    59.93  
   1920x1080     60.00*   59.94    50.00

I also have to say at the time of running the above commands, the Display Mode is set to Mirror instead of Join Displays. I am unable to Apply Join Display mode because the confirmation modal dialogue appears in the second screen which is not getting the signal.

From the outputs, it seems both displays have the same resolution of 1920x1080, but have a different frame rate. I am not sure if that is the problem and how to proceed from here. I appreciate any responses.

I tried running

xrandr --output HDMI-1-0 --mode 1920x1080 --rate 144.03

but it did not help. I don't think it was supposed to, but I tried it anyway.

Sundeep
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  • Based on the spec sheet of your Acer, the 144.03 MHz option is for the notebook display, not the external Dell. One question, though: have you checked that the Dell is set to accept input via HDMI rather than Display Port? I've been using an external Dell for years and have occasionally seen the input switch itself back to Display Port instead of HDMI. I need to set the input on the monitor maybe once or twice a year. –  Dec 22 '20 at 12:48
  • Thank you for responding. Yes, the Dell monitor Input Source menu has Auto, DP, mDP and HDMI/MHL options. By default, it is set to Auto. When I connect my mac, it automatically detects DP input. When I disconnect my mac and connect the HDMI cable to my Acer notebook, it detects HDMI as input, but the screen stays blank. – Sundeep Dec 22 '20 at 12:52
  • I'm sure you've done this, but you've also tried pressing [Fn]+[F5] a couple of times to trigger the notebook to use an external display, correct? –  Dec 22 '20 at 12:59
  • I remember trying it, but it could have been before I installed the drivers. I will try it again after I get off work and let you know. Thank you! – Sundeep Dec 22 '20 at 13:04
  • I don't know what changed, but sadly I am back to the monitor not being detected at all. Pressing [Fn]+[F5] doesn't change anything now. – Sundeep Dec 24 '20 at 21:40
  • Try using nvidia-settings. Archwiki has and article about this that may provide some help. Archwiki Multiheaded – da_kingpin Dec 25 '20 at 17:40

1 Answers1

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Please, try to lower the resolution from your monitor to Full HD and 60Hz and use Mirror Displays first. Does it work?. Is the external screen detected?.

If this works try to have the laptop's screen working at 60Hz and then extend the image.

I suspect that what happens is that the GPU is trying to use the same frequency for the external monitor than for laptops monitor. Then the external monitor does not support that frequency.

In other words, try to make it work at 1920x1080 FHD at 60Hz, the common for most mortals, and if that works lets start going for the higher specs. Should not be a problem to use the max resolution of the display, but I think the problem may reside on operating on different frequencies.

Cheers.

Carles Mateo
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