Note that tearing on all-but-one monitor in Xorg sessions is expected. It's an unfortunate feature of Xorg with DRI2. If you can convince the system to use DRI3 and TearFree then that avoids it. But that feature also doesn't exist for all graphics drivers.
Please run: lspci -k > lspcik.txt and attach 'lspcik.txt' as well as your $HOME/.local/share/xorg/Xorg.0.log ** Changed in: xorg-server (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1853094 Title: Screen tearing in xorg gnome session on Latitude 7480 with WD19TB Thunderbolt dock Status in xorg-server package in Ubuntu: Incomplete Bug description: I have the WD19TB Thunderbolt dock connected to a Dell Latitude 7480 laptop with two external displays. The laptop itself is closed (internal display is not used). In a gnome xorg session, there is severe tearing on parts of the screen when dragging windows or scrolling content. Under a wayland session there is no screen tearing, but I have keyboard key repetition problems which make this mostly unusable day- to-day (https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1849405). I can supply short phone videos of tearing occurring on the screens if required. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: mutter 3.28.4-0ubuntu18.04.2 ProcVersionSignature: Ubuntu 5.0.0-36.39~18.04.1-generic 5.0.21 Uname: Linux 5.0.0-36-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.9 Architecture: amd64 CurrentDesktop: GNOME Date: Tue Nov 19 14:02:09 2019 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_AU.UTF-8 SHELL=/bin/bash SourcePackage: mutter UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1853094/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp