Joining this conversation. I have a NUC with hd5000 graphics and an ASUS pq321 monitor. I realized I had been running it in 30hz since getting it.
Downloaded the newest Intel drivers offered by Windows Update and set up collage mode. In general works fine until I leave the machine for a while. I don't allow my machine to sleep, but it does turn the monitor off after a while. Once it does I can't get it to come back up with keyboard/mouse. I have to turn it off and back on. Once I do so and log back into Windows 8.1, all my open windows have shrunk down to a small size in the top left corner of the screen and there is a ghost taskbar in the middle top of area of the screen. Have to log off and back on for that to go away. Will try the latest drivers from Intel now.