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Hi I'm a bit new with Ubuntu so I'd like some help troubleshooting some issues I have with my display settings.

I've just set up an Odroid H2 with a fresh install of Ubuntu 18.04. I have it hooked up to my TCL 49S515 4K HDR TV via HDMI. Both the H2 and TCL have HDMI 2.0 ports and both products' specifications say they support 4K at 60 fps. The H2 has an Intel UHD 600 GPU, and I haven't touched anything with display drivers yet (I'm just running everything straight out of the box).

When I checked the display setting GUI and set the resolution size to 3840x2160 the highest refresh rate available to choose from is 30. I've also checked the display settings in a terminal using:

xrandr

Under the 3840x2160 size the highest refresh rate available is also limited to 30.0. If both the H2 and my TV support 4K at 60 fps why is there no option to select it? Is there any way around this?

bfrig
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3 Answers3

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I found the solution but it was unrelated to the suggestions proposed by others. I did some reading and found that the reason my refresh rate was limited to 30 Hz was due to my TV settings. In my TV settings there was a property "Input Settings", which allows you to set the HDMI protocol for each port. There were three options: 1.4, 2.0, and Auto. Mine was initially set to Auto, but I changed it to 2.0. After a reboot of my computer and checking my display settings with the xrandr I see the proper list of refresh rates for 4K, with 60 Hz being the recommended value.

Long story short...check your TV input settings too folks! Thanks for the suggestions.

bfrig
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I had the exact same problem with my 4K TV. The solution was to generate a 3840x2160 resolution with a 54 Hz refresh rate:

To summarize I used:

  • cvt 3840 2160 54

Then take the output from above and pass it to below:

xrandr --newmode "3840x2160_54.00"  637.50  3840 4152 4568 5296  2160 2163 2168 2230 -hsync +vsync

Finally set the monitor to the new resolution - refresh rate:

xrandr --addmode DP-1-1 3840x2160_54.00

The difference between 30 Hz and 54 Hz is night and day. At 30 Hz colors are washed out and causes eye strain.

WinEunuuchs2Unix
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(This is an answer to similar symptoms but a different cause, in case someone comes across this question.)

For anyone who is stuck at 30Hz after 60 was previously working just fine (perhaps after upgrading to 20.10), you can restore the refresh rate option by switching to Wayland, setting the display to 4k 60Hz, switching back to Xorg, and setting your desired display settings again. You'll have to do it after every reboot.

John LaRocque
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