Check if your PC uses UEFI or BIOS

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 PCs are shipped with UEFI support. To check if your PC supports and uses UEFI/EFI or BIOS, follow the steps highlighted below.

Check if your PC uses 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.

setup act

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


Callback_BootEnvironmentDetect: Detected boot environment: UEFI


If your PC supports and uses UEFI, the word UEFI will appear, else BIOS. (2) Alternatively, you can also open Run, type MSInfo32 and hit Enter to open System Information. uefi or bios If your PC uses BIOS, it will display Legacy. If it is using UEFI, it will display UEFI! If your PC supports UEFI, then if you go through your BIOS settings, you will see the Secure Boot option.

In general, UEFI-enabled machines have faster startup and shutdown times as compared to BIOS-based machines. Here is a list of Windows 10 features that requires UEFI:

  • Secure Boot protects Windows 10 pre-boot process against bootkit and other malware attacks.
  • Early Launch Anti-malware (ELAM) driver gets loaded by by Secure boot first and checks all non-Microsoft drivers before they are loaded.
  • Windows Trusted Boot protects the kernel and system drivers during launch.
  • Measured Boot will measure components from firmware till the boot start drivers & stores these measurements in the TPM chip.
  • Device Guard uses CPU virtualization and TPM support to support Device Guard with AppLocker, and Device Guard with Credential Guard.
  • Credential Guard works with Device Guard and uses CPU virtualization and TPM support to protect security information like NTLM hashes, etc.
  • BitLocker Network Unlock will automatically unlock Windows 10 at reboot when connected to a corporate network.
  • GUID Partition Table or GPT disk partitioning is required to enable large boot disks.

Hope this helps.

Posted by on , in Category Windows with Tags
Anand Khanse is the Admin of, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.


  1. Dan

    I never realized this before, but on my Acer 5736Z laptop with Windows 7 Home Premium 64 bit SP1, neither the “setupact” nor “BIOS Mode” entries appear in their respective places (as shown in your graphics); I wonder if this carries over to desktops re Home Premium?

  2. C:WindowsPanther there is no setupact.log file…….w8 Pro WMC > i7@Gigabyte P55USB3 Mobo… hidden file folder + show protected operating system folder

  3. ErnieK

    Even re-setting the security levels to full I still cannot access the setupact.log.

  4. odiebugs

    This is not the way you check to see if your system supports a UEFI boot, this is the way you check if the system is in Legacy (BIOS ) or UEFI. Just because Detected Boot Environment = BIOS,,, only means that windows was installed in BIOS mode. Please do not post the wrong info. To make sure you get this, a UEFI system can have windows installed with MBR in a BIOS mode, from your post, if someone installed windows in legacy, this means it’s not UEFI.


    If anyone wants to see if the BIOS has UEFI, you check with your MFG of the motherboard and see what BIOS it has and if it has UEFI support.

    There are OEM, that will install win 7 in MBR ( LEGACY ) when the system is UEFI capable, but with your post, they will think the system can’t be UEFI. Remember, most onboard IGPU have UEFI GOP support, and only the new PCI-E, GTX 700 series have UEFI GOP support to run in pure UEFI. If you have a NON-UEFI GOP support graphic card, you can still install windows in a GPT EFI mode, it just won’t be pure UEFI unless the GPU supports it.

  5. profkumasi

    Odiebugs, you are so right on point that, I feel like kissing you! Entering my setup (Lenovo ideapad Y530), I realized written AMI EFI meaning it is EFI/UEFI capable but my system runs in LEGACY moded.

  6. vinoth

    thr is no setupact.log file in hp envy 4 1002-tx ultrabook plz help and i want to install os x 10.9. when i hit boot option i’m getting clover something. plz help me to install. tankx

  7. me

    very helpful! THX

  8. NRev

    copy the file to desktop or documents folder this allows access when out side the “protected operating system”

  9. Bt

    I have Dell 990MT desktop and wanna add Nvidia Quadro k620 card which requires UEFI support and how to know if it works ?

  10. Casper42

    How do you change from Legacy ro UEFI native mode in AMI EFI?
    Friend has an ASrock and we can’t figure out where to change it.

  11. Sagyam Thapa

    no log file found

  12. Michael Heenan

    Says ‘Access is denied’ when trying to open setupact.
    All I want to do is install an unsigned driver.

  13. Per Sørensen

    At BOOT look closely at the bottom at the screen where it OFTEN says something like: press the ‘DELETE’ or in some cases it”s F1/F2 or some other key that will give You access to what some STIL CALL the BIOS, but in latter motherboards is the UEFI.
    BUT – IF UEFI is selected as the ‘startup mode’, then You might have discover that it”s difficult to access it.
    For some PC’s You’ll have to run a program under Windows, to make the PC BOOT into UEFI at next BOOT.
    Go to the producer of the motherboard or in the case of notebooks & laptops, go to the manufacturer of said PC, to see if they have a utility to make Your PC BOOT into UEFI.
    Hope this helps You out.
    Greetings PCDOK2REN.

  14. Rakchyas Shrestha

    For installing win 8.1, I converted MBR disk into GPT disk in win7 os and it asked to restart so i did n after that no display at all… It was nt starting…
    Please help me. I think motherboard didnt support GPT…what shall i do now??

  15. J Dsouza

    How to use UEFI if my PC has it instead of BIOS?

  16. Boomer

    My panther folder doesn’t have setupact. It doesn’t have most of those items! I have hidden folders shown, so it isn’t that. I have setup.exe and UnattendGC folders – both of which are empty. Then I have two XML documents entitled diagerr and diagwrn. How can I find out whether UEFI or not? Also on System Information mine doesn’t have Bios Mode either. I am using Windows 7 Professional.

  17. Greg

    Run a command prompt as administrator and type bcdedit. The results will return a “path” value (amongst other things). If it ends with winload.exe you are currently running in BIOS (legacy) mode. If it ends with winload.efi or bootmgfw.efi then you are currently running in UEFI.

  18. Saša Živkovi?

    I was having some problems with boot in WinX until I found out about this UEFI feature on new motherboards. After reading this post I found out that this was the problem since I know for a long time that my motherboard don’t have UEFI so I turned it off in Win X power settings. But here is my question:

    If during installation WinX knew that my motherboard don’t have UEFI (this is what WinX says in a log file from this post, BIOS not UEFI) why did it install it in a first place?

    I didn’t take any special install proc because I’d be aware of something like this since I’m not quite a novice to Windows OS.

    Anyone ?

    Thank you

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