ThinkPad L450 [Ubuntu 16.04.5 LTS, kernel 4.13]: 1920 x 1080, Intel HD Graphics 5500 & UltraDock – 90W EU (DisplayPort 1.2)

ThinkPad L480 [Linux]: 1.920 x 1.080 (IPS), Intel UHD Graphics 620 & Lenovo ThinkPad Ultra Docking Station - 135 Watt (DisplayPort 1.4)

Benq PD2700U - 16:9, 3840 x 2160 4K UHD (2160p)

Dell U2518D - 16:9, QHD 2560 x 1440 at 60 Hz

  • both monitors can daisy chain

I can set up the monitors with daisy chain OR via the 2 DisplayPorts outputs of the Docking with a resolution of up to 2560 x 1440 (and 1920 x 1080 for the Laptop screen) for the L450 and L480 (with the docking stations).

BUT when I change the resolution of the Benq 4K monitor to 3840 x 2160 (59.xx Hz) it results in

  • ubuntu: dell 2k monitor gets black (but is shown to be still connected in xrandr --verbose | grep " connected")

Errors are:

could not set the configuration for CRTC 65

required virtual size does not fit available size: requested=(8320, 2160), minimum=(320, 200), maximum=(8192, 8192)

requested position/size for CRTC 65 is outside the allowed limit: position=(4480, 0), size=(3840, 2160), maximum=(8192, 8192)

The result of

xrandr --output DP-2-1-8 --mode 3840x2160 --rate 29.97 --primary --output DP-2-1-1 --mode 2560x1440 --rate 59.97 --right-of DP-2-1-8 --output eDP-1 --mode 1680x1050 --rate 59.95 --left-of DP-2-1-8

result of 2k 4k 1080p

It happens via the 2 DP ports and via daisy chain (Benq 4K to Dell 2K).

  • there was one sentence about NixOS and it had addition information value, but fine I hope now you can state your knowledge about the situation related to Ubuntu. – InLaw Feb 10 '19 at 15:15
  • Ubuntu kernel 4.13 is EOL & unsupported (has had no updates in a long time), so I'd suggest you upgrade your system. Ubuntu 16.04.5 should be using kernel 4.4 or 4.15. I don't know NIX OS, but are you running Ubuntu? – guiverc Feb 14 '19 at 4:20
xrandr -v --output ${benq}  --mode 3840x2160 --rate 29.97 --primary \
          --output ${dellb} --mode 2560x1440 --rate 59.95 --left-of  ${benq} \
          --output ${pc}    --mode 1600x900  --rate 59.99 --right-of ${benq} 

with a lower refresh rate and a smaller resolution of the laptop monitor is it working all right

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