I have no idea if this is the place to ask but, here goes. In W8.1 device manager the SM Bus controller driver is missing. I have searched repeatedly and downloaded things that have not fixed this issue. Can someone help me please? Am I asking the wrong questions? Is there anything I should be searching for?
Well, certainly not in the Intel NUC forum.
Go to the gigabyte downloads for your board. There are multiple versions, so I cannot choose one for you. When there, download the chipset INF for your board and OS (presumably w8.1 64-bit) so your OS can properly identify the missing controller.