This is complementary info to the one in here.
I have LG 43UF770T and Gigabyte GTX 960 G1 Gaming 4GB.
The PC is set to 4K@60Hz and connected to the tv using HDMI 1 port. Only this port supports HDMI ULTRA HD Deep Colour in this tv. By default HDMI 1 icon is HDMI and HDMI ULTRA HD Deep Colour is off as written above. This results in chroma 4:2:0. I changed the setting as per instructions here, i.e. HDMI 1 port icon to PC and HDMI ULTRA HD Deep Colour to On. The nvidia settings are shown below.
To test the chroma for the default setup and the new one I used chroma torture test.
The results are here:
As can be seen, the top red, middle blue and bottom text is unreadable with the default tv settings on HDMI 1 port. With the new settings, everything is clear.