My R9 290X has three options:
My HDTV, the Vizio M50-C1, can only display 60Hz+ when using 4:2:2 format. If the format is 4:4:4, it is forced at 30Hz or less.
I got a DisplayPort 1.2 to HDMI 2.0 adapter from Club 3D to handle 4096x2160@60Hz; the problem is, unlike HDMI and DVI, Radeon Settings will not let me set the pixel format when using DisplayPort. It automatically seems to be forcing 4:4:4 and I am forced to use 30Hz.