I have been having extreme video tearing problems across multiple titles (dx9 - dx11) including
Assassins creed 4 Black flag
Shadow of Mordor
Grand theft auto 5 (running full screen mode)
For example in Black Flag I get around 40-45fps. Moving the mouse very slowly left to right I get about 4-8 horizontal tear lines appear (much more than normal without vsync on).
I'm used to a bit of video tearing without vsync on but this seems a bit extreme for the fps I am getting (turning on vsync does fix it).
Windows 10 Pro 64bit (clean install)
Tried 15.7.1 - 15.10 Beta
Asus Crosshair IV (890fx)
Asus Xonar Essence STX
860w corsair psu
benq v2420h (I've tried an acer monitor too and the same problem happens)