FirePro W8100 grapiccard but "tearing" - videos

Hello everyone,
sadly every Video I watch on youtube has some weird "tearings" .. It doesn't matter if I watch it on 144p or 1080p the "tearings" are there.
I also tried this test tearing test @29.97 fps (1080p) - YouTube


In past I thought the "tearing"-problem is because of my old "benq gl2460" (2ms) monitor.

So I decided to buy a new 1ms one (the "benQ ZOWIE RL2455")


Still the same problem ... so it has to be something with my graphiccard.


I really hope for help! Thank you!


My hardware:
-AMD Firepro W8100

- 256GB Samsung SM951 M.2 2280 PCIe 3.0 x4

-Intel Core i7 5820K 6x 3.30GHz So.2011-3

-32GB Ram DDR4


Maybe this is the problem:
I can't use "freesync"

Maybe I have to activate it somehow? But I don't know how.