HD=1920x1080 resolution is perfect for 15,6 inch laptop. 4K=UHD= 3840x2160 is overkill on 15,6 inch laptop - you can barely see the pixels if you look at the LCD through a magnifying glass. If you want to do CAD work on 15,6 inch 4K laptop, you have to hold mouse in one and and magnifying glass in the other hand. In other words, you must have 4K monitor if you want to do CAD work. By the way, we already had debate about 4k monitors: Should I get a 4k monitor?