This message was posted on behalf of Intel Corporation
Thank you for contacting us, I was reading your thread and I know that you need the assistance to work on Windows 8.1, as you already know this Intel® NUC support Windows 10 only, you can confirm this information in the following link:
What I can recommend is waiting until another community peer may be able to provide you any other work around.
I hope you can find the information you need
I understand that it's only Windows 10 support but I wanted to ask the community to see if anyone has modified the INF to get it to work with Windows 8.1, as they did for the 620/630 video cards.
Nothing less than windows 10 is supported. Upgrade to Windows 10, and avoid all of the problems. If you already have Windows 8.1, you have endured enough pain. Start the healing process and upgrade to Windows 10.