later edit: YES, you should either buy a DisplayPort cable, or use your monitor at 120 Hz or whatever resolution allows you to set Full RGB or YCbCr 4:4:4
The normal output of the video card is 4:4:4 Full RGB / YCbCr (YCbCr is just another way of representing color information for a pixel, instead of red,green and blue you have Y = brightness , Cb = chroma blue, Cr = chroma red)
4:2:0 reduces the color information (instead of sending the color information for every pixel, the video card makes groups of 4 pixels and computes an average for the color of those pixels and sends only that average. So instead of 4 pixels x 2 bytes per pixel, the video card sends only 2 bytes.
If you're watching a movie, then this 4:2:0 color subsampling won't affect you, since the videos are already encoded like that, to compress better. But if you're in Windows or you're gaming, then it's possible for colors to be washed out or for some things to be distorted or hard to read.
This color subsampling is especially easy to notice on colored text over a color background.
For example, see this article : https://www.geeks3d.com/20141203/how-to-quickly-check-the-chroma-subsampling-used-with-your-4k-uhd-tv/
You can use that test image (or the one attached to this post) to see how 4:2:0 can affect your image