How to Check If Your PC Uses UEFI or BIOS Firmware

Dave LeClair 25-04-2016

If you have a Windows 7 or 8.1 machine that you want to migrate to Parallels and it’s not working correctly, or you just want to know if you system is using UEFI or BIOS, getting the information is a little complicated. But don’t worry, because we’ll show you how to find out which boot environment Discover Your BIOS & Learn How to Make the Most of It What the heck is the BIOS, anyway? Is it really that important to know? We think so and fortunately it's pretty easy. Let us introduce you. Read More your computer is using.


First, use Windows Explorer to navigate to C:\Windows\Panther\setupact.log. Open the file in Notepad and look for the following:

Callback_BootEnvironmentDetect: Detected boot environment:

After the colon you will see either BIOS or UEFI. Whichever one is listed is your boot environment. If your reason for finding out is because you’re having issues with Parallels, version 9 and forward support UEFI, so you might need to pick up a new version if your system is running UEFI.

This PC 2016-04-24 13.56.55

If the setupact.log is missing, and you’re running Windows 8, 8.1, or 10, open a Run box, then type msinfo32. Look for the entry labeled BIOS Mode. If it says “Legacy,” then you’re running BIOS. If it’s anything else, it will be listed.

Why did you want to know which boot enviroment your computer is using? Let us know in the comments!


Image Credit: snig via ShutterStock

Related topics: BIOS, UEFI.

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  1. Bert
    December 19, 2016 at 8:16 am

    Today it was the same fake story you describe which happened here - somewhere in Germany. At first it was a woman, saying she calls from Windows because of a problem malware streaming out of my windows computer (haha!) and the she handed the phone over to a colleague, who politely wanted to give to me orders to fill in a special code in my computer system. I stopped him, saying that I can't follow and will call him back in five minutes. This he refused, but promised to call me back in a few minutes later, what he did. But meanwhile I googled, found and red your text which was very helpful. The number shown on my phone was: 0010023200100.

  2. Matt
    May 5, 2016 at 6:01 am

    Mine says legacy. Hardly surprising given that when I bought the motherboard Win7 was a still the latest thing.WHY did I want to know? Up until I read this article I'd never even thought about it - so what does knowing do for me? What difference does it actually make?

  3. Al
    April 28, 2016 at 10:21 pm


    My system is running BIOS

  4. dan
    April 26, 2016 at 2:37 am

    Like Dennis Primm, I too have a 'C:\Windows\Panther' folder but no 'setupact.log' in this folder.

  5. Anonymous
    April 25, 2016 at 9:55 pm

    Mine came up as EFI. Can I presume its the same UEFI????

  6. Dennis Primm
    April 25, 2016 at 4:35 pm

    I wonder why the "setupact.log" is missing from my system? The "Panther" folder is there, but no "setupact.log" file. I went ahead and ran "msinfo32" and my BIOS is "UEFI".

    I purchased this machine (a Toshiba Satellite C75D-B7300) new in December 2014 and it had Windows 8.1 Home preinstalled on it, which I updated to Windows 10 Home free when it first came out through Microsoft. It seems to me that its weird that the "setupact.log" file is missing. Doesn't it to you? Can you explain the reason for that anomaly?

    Thank you! Keep up the great work!!!