Tips on getting brightness to work over displayport? GTX960, 10.12, Samsung U28D590D

Gigabyte z170x gaming 7

I've tried a few things to no avail. Web drivers appear to be working, im pushing 3 4k monitors over display port and 1 1080p over HDMI simultaneously without issues.

I've been running OS X on this machine since yosemite, brightness has never worked.

Any tips?