Johan Arwidmark recently posted an article, “List of Windows 10 features that requires UEFI”
One of the many restrictions of the Windows 10 inplace-upgrade process is that it doesn’t support changing BIOS to EUFI (see my Windows 10 Upgrade Limitations post for complete listing). So, do you really need UEFI to deploy Windows 10? The answer is no, Windows 10 can absolutely be deployed to BIOS-based machines, but some of it’s features does require UEFI. Here is the (current) list:
Full article:
http://deploymentresearch.com/Research/Post/514/List-of-Windows-10-features-that-requires-UEFI
Firmware Security 