Well,
I sorted my particular problem  !!!!!

Windows 'says' it's shutdown and screen turns off properly, but Motherboard still stays running (fans. lights usb etc).

Answer ? I REMOVED the Samsung USB drivers for Mobile (to connect my Galaxy s6 to PC) 

PC now actually does proper shutdown AND restarts !!!!

Proved using another drive running Win 10 on same machine but without Samsung Drivers.
Windows Event Logs and fiddling with Bios and Hiberfile / Power settings etc doesn't even come in to it, IF you use another Win 10 fresh drive to prove these things.

Simple eh guys ?