So I went ahead and it works! At first it did 3840x2160 only at 30 Hz, but after rebooting it now runs at 60 Hz, at least according to xrandr (see below).
Is there a way to independently verify the refresh rate? Unfortunately the monitor doesn't display it. For the record, this is an Asus Zenbook 3 (UX390UA) with integrated Intel HD Graphics 620 connected to a LG 27UD88 4k display via the included USB-C-to-C cable. $ xrandr Screen 0: minimum 320 x 200, current 5760 x 2160, maximum 8192 x 8192 eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 276mm x 155mm 1920x1080 60.05*+ 48.04 1400x1050 59.98 1280x1024 60.02 1280x960 60.00 1024x768 60.04 60.00 960x720 60.00 928x696 60.05 896x672 60.01 800x600 60.00 60.32 56.25 700x525 59.98 640x512 60.02 640x480 60.00 59.94 512x384 60.00 400x300 60.32 56.34 320x240 60.05 DP-1 connected 3840x2160+1920+0 (normal left inverted right x axis y axis) 600mm x 340mm 3840x2160 60.00*+ 30.00 2560x1440 59.95 1920x1080 60.00 59.94 1600x900 60.00 1280x1024 60.02 1280x800 59.81 1152x864 59.97 1280x720 60.00 59.94 1024x768 60.00 800x600 60.32 720x480 60.00 59.94 640x480 60.00 59.94 HDMI-1 disconnected (normal left inverted right x axis y axis) On Mon, Jul 2, 2018 at 4:17 AM, Bryan Vyhmeister <br...@bsdjournal.net> wrote: > On Fri, Jun 29, 2018 at 11:04:12PM +0200, Maximilian Pichler wrote: >> Thanks for explaining. Some shaking could be lived with... > > I went ahead and bought a Plugable USB-C to DisplayPort cable to confirm > that there are no issues. I unplugged my mDP to DP cable from the > NUC6i7KYK and the HP Z27s 3840x2160 monitor and replaced it with the > USB-C to DP cable and everything works exactly as before. Running xrandr > reports that I am running on DP-2 at 3840x2160 at 60Hz. > >> I just realized that some monitors (e.g. LG 27UD88) can connect via >> USB-C directly, whilest serving as a USB hub and power source. Would >> this be expected to work as well? > > This type of thing should work fine as the other poster said also. This > charging functionality is not OS-dependent and should work because of > device firmware. USB-C can carry different types of signals that have > been around a while and can be quite convenient as a result. > > Bryan
