I just got a new laptop, ThinkPad T480 (with just the Intel UHD 620 graphics) and installed Ubuntu Mate 18.04.1.
I have it plugged in via an HDMI cable to an external monitor (Iiyama G-Master GB2488HSU).
Both screens are set to 1920x1080 @ 120Hz.
My external monitor exhibits flickering at random, but approximately every 5 to 10 minutes. The screen goes black for maybe 3 seconds before returning to the desktop.
I can’t find a solution despite an extensive search.
Some relevant bugs seem to include:
https://bugs.launchpad.net/ubuntu-mate/+bug/1558736
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1522922
As I understand it TLP is no longer installed on Ubuntu MATE 18.04, because it requires setting up an email server and the kernel power management has improved since 16.04.
Any advice would be appreciated because this is an annoying problem on what should be a well supported laptop for Linux.