I've installed new win8.1pro license on additional 500GB HDD after I got NUC6CAY, but I couldn't find where to download their driver, please advise. Thanks.
Note: our company purchased lot of win8.1pro license from Microsoft dealer, and we must use Pro version because we manage our user through domain controller.
Windows 8.1 is not supported on your NUC:
https://www.intel.com/content/www/us/en/support/articles/000005628/mini-pcs.html Supported Operating Systems for Intel® NUC Products
What drivers there are can be found here:
https://ark.intel.com/products/95062/Intel-NUC-Kit-NUC6CAYH Intel® NUC Kit NUC6CAYH Product Specifications
Well, there are two choices. First, you could try installing Windows 10 using a Windows 8.1 key. I have done this in the past, but Microsoft may have dropped support for this capability. Second, you could try using the NUC5CPY instead. You'll have to analyze whether it actually meets the requirements for your usage model.