4:4:4 Color improves the color volume of the Parsec stream. It is helpful in situations where color clarity is important, like graphic design, video/photo editing, animation and colored text rendering.
On the client 4:4:4 Color is significantly more performance hungry than the regular Parsec stream (4:2:0), as it requires software decode (CPU) on the client side. This means performance or battery life on the client may be less when using this feature.
4:4:4 is only supported by NVIDIA hosts running GTX 900 (Maxwell), GTX 1000 (Pascal) and RTX 2000 (Turing) consumer graphics cards, and their respective Quadro workstation cards.
4:4:4 + H.265 is only supported by GTX 1000 (Pascal) or better.
You can verify 4:4:4 is working by checking the overlay .
The default Parsec stream is 4:2:0 which is standard for video encoding.
A technical comparison chart between luma (black and white pixels) vs chroma (color pixels) for each chroma format. (Source RTings.com)