Running the command below, I expect the external monitor resolution to be changed to 4K. Although xrandr states my desired mode as active, it remains 1366x768:

xrandr --output DP2 --mode 3840x2160 --rate 24

$ xrandr

DP2 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
   3840x2160     30.00   25.00    24.00*    29.97    23.98    29.98  

The maximal resolution I get is 1920x1080 using this command:

xrandr --output DP2 --mode 1920x1080


  • Notebook - Lenovo Thinkpad X220 with Intel 3000 HD Sandybridge
  • Ext. Monitor - AOC 4K U2777PQU1 with 23Hz minimum vertical scanrange2
  • Connection - Displayport via notebook dockingstation

Officially Intel's Sandybridge can not output 4K. Unofficially it can: Resources



1 https://manuals.coolblue.nl/8c/aoc-u2777pqu.pdf

2 img

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