Ubuntu
xorg-server package

  1. Bug #1890418
  2. Comment #6

Comment 6 for bug 1890418

Revision history for this message
Daniel van Vugt (vanvugt) wrote : Re: External monitor will not display to 4k

Thanks. The file xrandr.txt indeed shows the HDMI connection is limited to 1920x1080. It also shows that's the "current" mode but it lists no "preferred" mode, which does support the idea that the monitor can do higher resolution...

The manufacturer's specs mention that 4K is limited to 30Hz over HDMI. But that should be fine. It just means the monitor can't do HDMI 2.0. Most likely the monitor only supports HDMI 1.3 or 1.4.

I think the main problem here is probably the HDMI cable. If it can only handle HDMI 1.2 or lower then you will not see the 3840×2160 30Hz option. So I suggest getting a newer cable that supports at least HDMI 1.3.

Why Windows 10 doesn't have the same issue, I don't know.