Zones on 26 March 2017
You don't need to buy an adapter to get 4K @ 60 Hz.
Simply connect your R9 390X from its HDMI slot to your port 1 HDMI slot of the TV via an HDMI 2.0 cable that is preferably less than 3 meters.
Anything extra would be a waste.
Edit: Nevermind, you will need the following to get 4K @ 60 Hz with 4:4:4 chroma subsampling support...
https://www.amazon.com/Club3D-Displayport-1-2-HDMI-CAC-1070/dp/B017BQ8I54
I initially thought R9 390X has an HDMI 2 slot.
