I want to achieve 2560x1440 resolution output from my laptop. I have a Dell XPS 15 (L521X) laptop on Ubuntu 16.04 and I want to output my screen to an external monitor from mini DisplayPort (laptop) to DisplayPort (BenQ GW2765 w/ 1440p). When I plug it in, the laptop screen & mouse freezes for ten seconds, and resumes, but the external monitor does not detect anything. I tried toggle display options (single, mirror, external, etc.) to no avail.

  • The XPS has a dedicated Nvidia GeForce GT 640m + HD 4000 integrated graphics card.
  • The cable is the latest Cable Matters Gold Plated Mini DisplayPort (Thunderbolt Port Compatible) to DisplayPort Cable, Black, 6 Feet (101007) from Amazon.
  • I've connected the cable to a Macbook Pro's thunderbolt port and it works perfectly on the monitor at 2560x1440 resolution.
  • When I connected HDMI to HDMI, it works fine, but only outputs 1920x1080 resolution. I really want the 2560x1440.

Any ideas on where to start or troubleshoot this?

1 Answer 1


I have the same laptop as well with 3 monitors (including the build-in) using the nouveau drivers, nvidia-361.41 that comes with ubuntu 16.04 does seems working pretty well especially with the mini display port.

Which display drivers are you using?. Have you try the HDMI port instead?

Another solution may try add a new mode by yourself by using xrandr:

xrandr --listmonitors

detect your monitor name usually the monitors attached in the mini display ports named as DVI-D-1-1 (at least in mine L521X):

xrandr --newmode MyNewNode ...

check the manual for the other arguments and then add the new mode at the right output:

xrandr --addmode DVI-D-1-1 MyNewNode

it going to detect the mode automatically when you plug the display or you can explicitly set the mode but better be careful with that:

xrandr --output DVI-D-1-1 --mode MyNewMode
  • Sorry i haven't noticed the 3rd bullet. You can try add the mode at the HDMI too it's the same process but the monitor should named as HDMI1. But I believe if you are using nvidia drivers switch to nouveau and it should work, Jun 20, 2016 at 18:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .