I have bad graphics on a fresh install Fedora 27 and NUC6i7KYK and a Dell P2715Q (4K monitor).
Moving the window of a bowser or terminal, shows the borders full of little white and black squares.
This also happens when scrolling a page in a browser
I had a much simpler machine with Fedora 20, a Geforce GTX960 card (with the NVIDEA driver) and the same monitor without having this problem.
Fedora is not supported on your NUC
https://www.intel.com/content/www/us/en/support/articles/000005628/mini-pcs.html Supported Operating Systems for Intel® NUC Products