Yes it sounds/looks like a signalling frequency problem if not a cable
Check out bug 1606103 where some frequency problems with the modesetting
driver are being investigated.
You received this bug notification because you are a member of Ubuntu-X,
which is subscribed to xorg-server in Ubuntu.
1920x1080 HDMI output is corrupted in 16.04
To manage notifications about this bug go to:
Mailing list: https://launchpad.net/~ubuntu-x-swat
Post to : firstname.lastname@example.org
Unsubscribe : https://launchpad.net/~ubuntu-x-swat
More help : https://help.launchpad.net/ListHelp