I can provide more screenshots if necessary but it is clear as day.
I'm not the only one who are having these issues. Reported a few a times, but doesn't even get noted as a bug but it is a very noticeable one.
I don't remember having those lines on 6850 but they were on 7850 and are on RX480. These bugs first appeared on GCN cards, the 5xxx and 6xxx series had no issues.
At Blizzard's forum: http://us.battle.net/forums/en/d3/topic/14277198081?page=1
Will Blizzard / AMD ever fix these bugs?
Please fix it AMD!