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I have a Thinkpad T440s running 15.04 with the Intel HD 4400 graphics. I just got a 4K monitor (Dell P2415Q). According to the specs of the HD4400, I should be able to drive this monitor at 30hz at 4K resolution. I have used this computer to do exactly that. Note that I am connecting via displayport.

Running xrandr gives

Screen 0: minimum 8 x 8, current 4480 x 1440, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+360 (normal left inverted right x axis y axis) 309mm x 173mm
   1920x1080      60.0*+   59.9  
   1680x1050      60.0     59.9  
   1600x1024      60.2  
   1400x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9  
   1280x960       60.0  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
DP1 connected 2560x1440+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
   3840x2160      60.0 +
   2560x1440      60.0* 
   2048x1280      60.0  
   1920x1200      59.9  
   1920x1080      60.0     60.0     50.0     59.9     30.0     25.0     24.0     30.0     24.0  
   1920x1080i     60.1     50.0     60.0  
   1600x1200      60.0  
   1600x900       60.0  
   1280x1024      75.0     60.0  
   1152x864       75.0  
   1280x720       60.0     50.0     59.9  
   1024x768       75.1     60.0  
   800x600        75.0     60.3  
   720x576        50.0  
   720x480        60.0     59.9  
   640x480        75.0     60.0     59.9  
   720x400        70.1  
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

It seems like I need to add a mode to run 3840x2160 at 30 Hz.

cvt 3840 2160 30
# 3840x2160 29.98 Hz (CVT) hsync: 65.96 kHz; pclk: 338.75 MHz
Modeline "3840x2160_30.00"  338.75  3840 4080 4488 5136  2160 2163 2168 2200 -hsync +vsync

Proceeding:

xrandr --newmode "3840x2160_30.00" 338.75  3840 4080 4488 5136  2160 2163 2168 2200 -hsync +vsync
xrandr --verbose --addmode DP1 "3840x2160_30.00"

Finally:

xrandr --output DP1 --mode "3840x2160_30.00"

When I do this, the monitor flickers for a second, then goes back to 2560x1440 @ 60hz. Running xrandr again:

Screen 0: minimum 8 x 8, current 4480 x 1440, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+360 (normal left inverted right x axis y axis) 309mm x 173mm
   1920x1080      60.0*+   59.9  
   1680x1050      60.0     59.9  
   1600x1024      60.2  
   1400x1050      60.0  
   1280x1024      60.0  
   1440x900       59.9  
   1280x960       60.0  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
DP1 connected 2560x1440+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
   3840x2160      60.0 +
   2560x1440      60.0* 
   2048x1280      60.0  
   1920x1200      59.9  
   1920x1080      60.0     60.0     50.0     59.9     30.0     25.0     24.0     30.0     24.0  
   1920x1080i     60.1     50.0     60.0  
   1600x1200      60.0  
   1600x900       60.0  
   1280x1024      75.0     60.0  
   1152x864       75.0  
   1280x720       60.0     50.0     59.9  
   1024x768       75.1     60.0  
   800x600        75.0     60.3  
   720x576        50.0  
   720x480        60.0     59.9  
   640x480        75.0     60.0     59.9  
   720x400        70.1  
   3840x2160_30.00   30.0  
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

Not sure what to do from here. Is this a hardware issue? Am I doing something wrong?

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  • Do you find solution for you problem?
    – Rage Steel
    May 20, 2016 at 9:21

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