Try 1080 anyway?
Recent Win10pro update on i7, 8gb, HD4000, 80gb msata
during browsing screen res switched down from 1080 to 768.
Checking screen display settings says 768 (recommended res).
Ran hardware check, all ok
Updated bios from A06 to A10, no change
Reinstalled display and chip drivers, no change
Any ideas other than OS rebuild?