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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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  • Assuming that you've got a decent HDMI cable (not the $2 type), one of the spec sheets is probably fibbing. Are any of the HDMI ports on the TV marked differently? ARC/MHT? Try connecting the TV to a different 4K source and see what you get. – heynnema Jan 11 '20 at 20:04
  • @heynnema makes a good point. The HDMI cable has to support 4K @ 60 Hz. A lot of older cables (and some cheap new ones) do not support his rate. Basically look for 15 Gigabits per second I believe the spec is. – WinEunuuchs2Unix Jan 12 '20 at 23:15

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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  • Choosing HDMI 2.0 instead of Auto worked on my TCL 49S405 as well. Now I'm using 4K at 60 Hz, with TV presets on Picture Mode "Sports" with Game Mode "On." Both the cursor and window motion feel snappy now, and text is much more visible than it was using other picture modes. – Chris Betti Feb 16 '21 at 17:23
  • Hey, thank you for this post. This was my issue too. On my Samsung TV, i had to go to Settings -> General -> External devices -> HDMI UHD Color -> select current hdmi channel ubuntu was using. TV did a quick blink, and then ubuntu was automatically on 60hz. – Terje Nesthus Apr 02 '22 at 21:51
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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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  • what is DP-1-1 ? – Qui-Gon Jinn Jan 12 '20 at 19:59
  • @Qui-GonJinn DP-1-1 is the name of the monitor reported by xrandr. Other common names are VGA, HDMI and eDP (laptop display). Substitute my display (DP-1-1) name with your own name. – WinEunuuchs2Unix Jan 12 '20 at 20:07
  • I followed your steps first by running: cvt 3840 2160 54

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

    Then ran: xrandr --addmode HDMI-2 3840x2160_54.00 From here I can see the 3840x2160_54.00 mode available in the list when running xrandr, but when I change to that mode the framerate doesn't seem to change at all. Even in the display setting GUI I can now see 53.98 Hz as an option for 3840x2160 resolution, but selecting it doesn't seem to change the resolution on my TV screen. Any thoughts?

     – bfrig Jan 12 '20 at 21:44
  • @bfrig --newmode "3840x2160_54.00" 637.50 3840 4152 4568 5296 2160 2163 2168 2230 -hsync +vsync are my settings you have to use your settings reported by cvt command. Also _54.00 is the highest refresh rate that worked for me. First I started at _45 and worked my way up from there. – WinEunuuchs2Unix Jan 12 '20 at 23:07
  • it doesn't work for me. i have this message: X Error of failed request: BadName (named color or font does not exist) Major opcode of failed request: 140 (RANDR) Minor opcode of failed request: 16 (RRCreateMode) Serial number of failed request: 32 Current serial number in output stream: 32 – Qui-Gon Jinn Jan 13 '20 at 00:40
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    @Qui-GonJinn Please post into a question what you typed in and what the results were and then link that question to me here. – WinEunuuchs2Unix Jan 13 '20 at 00:48
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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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