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In my Ubuntu 20.04 display settings on a Dell Latitude 7490 laptop, I can set my laptop monitor to 1920 x 1080 resolution at 60 Hz, but I cannot set my AOC CU32V3 32" 4k monitor to 60 Hz (see screenshots below), even though the monitor supports it. It feels laggy, so I'd really like to increase the refresh rate to 60 Hz. Any idea how I can do this?

Laptop monitor is 60Hz: enter image description here

External monitor supports 4k (3840 x 2160 resolution) at 60Hz refresh rate, but I cannot set it to 60Hz: enter image description here

Notice there's no 60Hz option: enter image description here

Proof the manufacturer says it supports 60Hz at 4k:

https://us.aoc.com/en/monitors/cu32v3 enter image description here

Info on my laptop's graphics card (Intel HD Graphics 620):

I'm currently connected with a High Speed HDMI cable in HDMI 1.2 mode. Am I to understand that I must use a USB C to Display Port adapter and the Display Port to get 4k at 60Hz, perhaps, instead of HDMI?

enter image description here

Related:

  1. https://www.dell.com/community/Latitude/How-to-have-Latitude-7490-to-use-4k-display-with-60Hz/td-p/6085124
Gabriel Staples
  • 9,155

2 Answers2

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It turns out it was just a hardware limitation of HDMI, so you have to use Display Port instead! So, I bought this USB C to Display Port adapter for $15 (you can try this one or this one if that one is out of stock), plugged in my Display Port cable that came with the monitor into it, and voila! It works perfectly! 4k (3840 x 2160 resolution) at 60 Hz is now an option and it works perfectly!

Note: if your computer doesn't have any USB-C ports with DP video support built into them, you'll need to use a DisplayLink USB A 3.0 adapter instead, as I explain in great detail in my other answer here: USB video card adapters for Linux Ubuntu. The $90 Club3D CSV-1477 USB 3.0 Type A to dual 4k 60Hz adapter, for instance, is excellent. I've tested it on both Ubuntu 20.04 and 22.04 with 4k @60Hz video output. It supports 5K @60 Hz single-output or 4k @60 Hz simultaneous dual-output.

Gabriel Staples
  • 9,155
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    Correct, this was also my solution. HDMI doesn't support 4k@60Hz. USB-C-to-DP1.2 cable is the solution. Thanks for writing it up. Incidentally, you answered my question on whether 4k@60Hz is possible through USB-C-to-DP cable on modern laptops running Ubuntu. Fab! – Cornelius Roemer Nov 21 '20 at 17:56
  • But this will only work if your laptop does have DisplayPort on USB-C and not if it just has SuperSpeed USB. – w-sky Oct 20 '23 at 20:03
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    @w-sky, correct. In that case, see my other answer here. I updated this answer accordingly. See above. – Gabriel Staples Oct 20 '23 at 20:47
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You need HDMI 2.0 cable and HDMI 2.0 capable graphic card for 4K @ 60 Hz. Your laptop only supports HDMI 1.4 hence the limit to 4K @ 30 Hz

https://www.dell.com/community/Latitude/Latitude-7490-Connecting-an-external-1080p-and-a-4K-display-lid/td-p/7433161

Petr Ketner
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  • 30 Hz as the highest VESA compatible refresh rate, but with tools like xrandr and autorandr you can get it slightly higher. I don't know the maximum refresh rate for full 4K but for UWQHD (3440x1440) it is 56.048 Hz through HDMI 1.4. – w-sky Jan 11 '24 at 23:18