I have a NUC8I7BEH3 which operates as it should however I get severe eye strain within an hour of use, and at times headaches.
I have updated W10 Pro to the latest version and also ensured my drivers are up to date in case there were issues in older versions.
I also am part of a forum called LED Strain (https://ledstrain.org) and it is believed that dithering may be one reason why a minority of users experience discomfort.
I really like the machine and do not want to return it, however it is almost unusable due to the eye strain.
I have confirmed resolution/refresh rate is all correct and I adopt 20/20/20.
I setup a NUC8i7BEH for a friend and noticed no such issues. We used a quality 2K monitor, the text and colors were perfect. The friend is 75 and her vision is not the best, but she absolutely loves the nuc and her monitor. My vision is also not the best, and I had no problems.
So, tell us about your monitor. Provided details, model number, connections, and cable information.