How to test whether Windows 10 was installed with UEFI?

Open the System Information Utility (Win Key + "R" > "msinfo32" > OK)

In system summary, look for "BIOS MODE".


Alternatively, check Disk manager. If you have a partition on your disk for "EFI system partition" then you are using UEFI. If you only have system reserved and C:, its probably BIOS.


Hope one of these helps


You can also use Windows Panther directory logs:

type C:\Windows\Panther\setupact.log|find /i "Detected boot environment"

Extracted from: http://www.sysadmit.com/2017/04/windows-uefi-o-legacy-bios.html