Trying to use a 4k monitor with Win7 will result in too-small-to-read text displayed on screen for normal Win7 file information (name, date of modification, etc.) because of the dot matrix used by Win7 for text characters. If you try to use Win7 text magnification option (125%, 150% etc.) that will appear to fix the legibility issue, until you run across an application that manages its own screen layout UI and suddenly text does not properly fit within the space aloted, or other problems. That is why Win10 is needed, to handle the issues of text display on a monitor with 2560x1440 pixels or more, with a bit more elegance than Win7. Using a really large diameter high res monitor alleviates the tiny text readability issues more than a smaller physical size monitor.