When I try to use display port on my monitor, it glitches out whenever I do anything

I just got a BenQ GW2765HT monitor today, and I tried to hook it up with the provided display port cable to my r9 390. The screen glitches out and cuts out whenever I move the mouse, or really do any updates on screen. Currently I have it hooked up through hdmi to type this post.

Is there certain set up to be able to use display port? I've never used it before. Either this monitor's display port..port is broken, the cable is, my GPU, or I'm an idiot.