Long time Windows users might be well aware of the term – UEFI. For those who are not, UEFI is the abbreviated form of Unified Extensible Firmware Interface, a sort of BIOS replacement to set up the hardware and load and start an operating system. It was first introduced by Intel as Intel Boot Initiative which was later changed to EFI. Later, EFI was then taken over by the Unified EFI Forum and was therefore named as UEFI.
UEFI comes with a boot manager which removes the needs for a separate boot loader. Besides, it gives you faster start-ups and better networking support. Most recent Windows 8 PCs are shipped with UEFI support. To Check If Your PC Supports UEFI/EFI or BIOS follow the steps highlighted below.
Check If Your PC Supports UEFI or BIOS
(1) Open File Explorer and navigate to the following folder:
C:\Windows\Panther.

In the folder named Panther you will see a text file titled
setupact.log. The file will automatically open in Notepad.

Once you have opened setupact.log, click Ctrl+F to bring up the Find box and search for an entry named
Detected Boot Environment.

Once you find Detected Boot Environment, you will notice the words BIOS or UEFI mentioned as follows:
Callback_BootEnvironmentDetect: Detected boot environment: BIOS
OR
Callback_BootEnvironmentDetect: Detected boot environment: UEFI

If your PC supports UEFI, the word UEFI will appear, else BIOS.
(2) Alternatively, you can also open
Run, type
MSInfo32 and hit Enter to open
System Information.
source:thewindowsclub