lg c2

Hello, ive tried everything and can't seem to get 4k 120hz. I've tried with 4 different ultra certified HDMI cords and 2 different TVs. On my 42" LG C2 with deep color 4k enabled when I switch to 3840 x 2160 120hz under PC display in Nvidia control I lose display. I then have to turn off 4k...