I'm having a Thinpad T440s with Intel HD 4400 graphics chip. The internal display works great. While an external monitor connected via Mini Displayport stays black. XRandR recognizes multiple outputs but shows all, except for eDP1, as disconnected:

Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
   1920x1080     60.05*+  59.93  
   1680x1050     59.95    59.88  
   1600x1024     60.17  
   1400x1050     59.98  
   1280x1024     60.02  
   1440x900      59.89  
   1280x960      60.00  
   1360x768      59.80    59.96  
   1152x864      60.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   640x480       59.94  
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)

I had no possibility to test if the VGA port works.

  • Is this one of the Thinkpad models with "optimus" dual Nvidia and Intel graphics? I discovered that with mine, the Intel just isn't connected to the external ports; you must use the Nvidia card. – mattdm Feb 12 '15 at 16:29
  • Hm, this might be possible. How can I find out, whether it has optimus or not? lspci did show only one VGA compatible device. – white_gecko Feb 12 '15 at 19:07
  • On mine, it shows up in the bios. You might have disabled optimus/nvidia. I did on mine initially until I discovered this exact issue. (There are some experimental hacks to get Optimus working, but easiest is to just use the Nvidia card. Should work with Nouveau, unless you need serious 3D) – mattdm Feb 12 '15 at 19:14
  • Finally it worked after a reboot. Should I better delete the questing, since it doesn't really seam to be a structural problem or something like that? – white_gecko Feb 19 '15 at 10:34

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