I have a NUC 5i7RYH with 16GB RAM running Windows 10. Until recently I had an older ASUS touch monitor (1600x900) connected via DisplayPort to DVI-D cable and it worked just fine. one week ago I upgraded to a Samsung UHD monitor (U28E590D) connected via DisplayPort to DisplayPort cable. I get full UHD resolution (4K @ 60Hz) this way, but it also created some issues. The primary one is that nothing displays on the monitor until the Windows 10 lock screen comes up. None of the NUC boot-up (pre-Windows) screens ever display. If instead I use an HDMI to HDMI cable to HDMI-2 on the monitor (4K @ 29Hz), the pre-windows screens do display. I have the latest graphics card driver from Intel installed. There are other issues, which I will describe in another posting, but this one really has me perplexed.