Unified Extensible Firmware Interface (UEFI) Explained

What is Unified Extensible Firmware Interface (UEFI)?

The Unified Extensible Firmware Interface or UEFI refers to a particular specification of a software interface between the operating system and the firmware.

Technically, it is superior and programmable and therefore the OEMs can add boot-time services and applications.


  • UEFI is considered to be more powerful and comes with more advanced features and functionalities than BIOS.
  • This firmware ensures faster boot time and more security to the computer with Secure Boot.
  • It is the next generation of BIOS that increases the performance of a system with detailed settings menu, 32 bit and 64 bit support and more addressable address space.

Understanding Unified Extensible Firmware Interface (UEFI)

What is Unified Extensible Firmware Interface (UEFI)

UEFI works just like BIOS but with enhanced booting speed, manageability, security and control.

Using UEFI will boot the system properly but you should do it correctly or else it will prevent the system from booting properly.

Therefore, without proper knowledge of it and an excellent reason for it, you should refrain from accessing the firmware of the motherboard.

Changing the UEFI settings will increase the speed due to faster boot time and its discrete driver support.

If you do it correctly then some of the notable benefits that you will enjoy are:

  • A more detailed setting menu
  • Secure Boot support to avert damages due to malware
  • Two mode support in 32 bit or 64 bit and
  • An increased addressable address space.

However, if you simply change to UEFI from CSM/BIOS the computer system will not boot up.

This is because Windows typically does not allow booting in BIOS mode from GPT disks.

This means you will need to have an MBR disk for that. And, since it does not support booting in UEFI mode from MBR disks, you will need to have a GPT disk.

Moreover, you should not do anything specifically if your system is running on Windows 11 because UEFI mode will be automatically enabled by default on the system.

The change in the settings will also delete all data, partitions and the operating system. This means that you will have to reinstall it right from the beginning.

However, when you make a change, make sure that you do not omit or overlook any of the requirements for it, both in your system and otherwise.

Doing so may result in a system failure and even some serious hardware issues in a few cases.

UEFI Boot Mode and Process

There are actually two boot modes such as UEFI boot mode and Legacy BIOS boot mode.

The process to follow to boot into one of these modes needs removing some files first and then following the boot up process.

To boot in UEFI mode you will need to remove the bootmgr file from Windows PE root or Windows Setup media to prevent the computer starting in BIOS mode.

And, to boot in legacy BIOS mode you will need removing the efi folder from the same to prevent the system from starting in UEFI mode.

The other processes to follow are:

  • Accessing the BIOS Setup utility
  • Selecting Boot from the screen
  • Selecting UEFI/BIOS Boot Mode from the Boot screen
  • Pressing Enter
  • Selecting either UEFI Boot Mode or Legacy BIOS Boot Mode by using the up and down arrow keys
  • Pressing Enter
  • Pressing F10 to save changes and exit.

UEFI Firmware Settings

The UEFI firmware settings will help you to set it up as well as fix a corrupted UEFi or even fix missing UEFI settings on your system.

Assuming that you know how to access UEFI on your computer system, there are a few different ways to set a few things in it.  

Steps to follow to set Surface UEFI are:

  • Set or change the UEFI password in the security section
  • Turn on or off Secure Boot
  • Change SMT or Simultaneous Multithreading settings
  • Turn on or off all connected devices in the devices section
  • Change the way the system boots in the Boot configuration section
  • Enter a new date and time manually in the Date and Time section
  • The About page here will displays the regulatory information and safety warnings
  • Select Exit and Restart now to save the changes and
  • Restart the computer.
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Settings to reset corrupted UEFI on a computer are as follows:

  • Press and hold the Shift key
  • Click on Restart
  • Select Troubleshoot
  • Go to Advanced options
  • Select UEFI Firmware Settings option
  • Select Restart option
  • Enter BIOS settings
  • Click on Restore Settings button (Or, press F9 if there is no such option and click on Yes on Default Options prompt to restore BIOS to default) and
  • Click on save and exit.

The steps to fix missing UEFI firmware settings are:

  • Verifying the system is equipped with UEFI
  • Bypassing fast startup function
  • Creating a shortcut for Boot to UEFI Firmware Settings
  • Converting MBR disk to GPT to change BIOS to UEFI and
  • Clearing CMOS or Complementary Metal Oxide Semiconductor settings to restore default BIOS settings.

What is UEFI Used for?

UEFI is used to set the hardware of the computer to work even before the operating system is loaded. It is also used as a new means for the operating system and the firmware of the platform to communicate and for defining the firmware services used for booting the operating system on the platform.

It is also used for some runtime services such as:

  • For faster booting of the system
  • For using bigger hard drives
  • For having more security assurance
  • For using better and more useful features
  • For having more mouse cursor and graphics options and
  • For using a lightweight BIOS alternative.

How to Change BIOS to UEFI?

First of all, you should change it with extreme caution because any small error may result in irreversible damage.

Next you should know the prerequisites and ensure that your system is ready for upgrading into BIOS. 

The things to check to ensure your computer system is ready to make a switch are:

  • The version of the operating system should be Windows 10 v1703 or higher
  • The targeted disk must not have more than three partitions and if there are more either merge or delete them
  • The BitLocker should be disabled or suspended so that it allows Windows to convert the drive from BIOS to UEFI
  • You should have proper backup of your data though losing your data due to the switch is ruled out and
  • Finally, ensure that the firmware setting is changed from BIOS to UEFI after the conversion.

Now you can start the conversion process by following these specific steps:

  • Press Windows and X keys at the same time on the keyboard
  • Select Shut down or sign out
  • Click on Restart and hold the Shift key
  • If the system has not boot into Advanced Startup screen, click on Troubleshoot
  • Select Advanced option from the window that follows
  • Click on the Command Prompt
  • Type mbr2gpt /validate in the Command Prompt window
  • Click Enter
  • (If the disk is not validated you should type mbr2gpt /validate /allowFullOS in the Command prompt window)
  • Type the command mbr2gpt /convert when the disk is validated
  • Wait for the conversion process to be completed
  • When done, reboot the computer system
  • Launch the firmware settings screen and
  • Switch from BIOS to UEFI.

You may verify whether it has really changed from the system information.

Is UEFI Secure Boot?

It can be said so because Secure Boot is one specific attribute of the most modern Unified Extensible Firmware Interface specification.

This is called Errata C and defines the new interface between the firmware or BIOS and the operating system and also helps the computer to resist infection and attacks from malware.

This feature allows running only authentic third-party firmware code in the firmware environment of the Original Equipment Manufacturer or OEM. It ensures that in actually two steps such as;

  • Verifying the boot image and
  • Verifying the updates in the database of the image security.

This is actually done by following a specific verification flow and by using a precise image/key security database.

How to Check Whether the Motherboard Supports UEFI?

Typically, you can check it easily in the BIOS and look for a UEFI/Legacy or a Secure Boot option switch in the System Information tab. If you find any of them then you can rest assured that the motherboard of your computer supports UEFI.

If this does not help, then there is another easy way to check it which is through the Command Prompt. The steps to follow are:

  • Go to Start
  • Type “cmd”
  • Right click on Command Prompt to open it as an Administrator
  • Choose Run as administrator
  • Type “bcdedit”
  • Go to Windows Boot Loader and
  • Look for the path line.
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If you see there that the extension for the “winload” file is .exe, then the motherboard is running a legacy BIOS and if it is .efi then it supports UEFI.

Alternatively, you can check the manufacturer of the motherboard and its model name and look for System Information in their official website to find whether or not it supports UEFI.

All of the above methods are applicable if you have a Windows operating system.

However, if you are using an Ubuntu or Debian based distribution, you will have to install the efibootmgr package to find out whether or not your motherboard supports UEFI.

However, this may be a long process. The shorter and easier one is to simply find a folder called /sys/firmware/efi.

If you cannot, your motherboard does not support UEFI and if you do, it does. It is as simple as that!

How to Install UEFI on Windows 10?

Installing Windows 10 will need a GUID Partition Table and you will also have to perform Windows 10 installations to enable UEFI. The first thing to do is install UEFI Windows 10 and then confirm whether or not it has been installed correctly.

The first part of the processor involves:

  • Connecting the USB Windows 10 UEFI install key
  • Boot the system in the BIOS by using F2 or the Delete key
  • Look for the Boot Options menu
  • Enable Launch CSM
  • Set Boot Device Control to UEFI Only
  • Set Boot from Storage Devices to UEFI driver originally
  • Set Boot from Storage Devices
  • Save the changes made
  • Restart the computer
  • Re-enter to BIOS
  • Confirm USB UEFI OS Boot option at the top of the Boot Priority list
  • Reboot the computer system and finally
  • Install Windows as you do normally.

Next you will need to confirm whether or not Windows has installed in the GPT partition by following these specific steps:

  • Boot into Windows
  • Open Disk Manager
  • Look for the three partitions which includes EFI System Partition
  • Right click the disk on Disk x, Basic, Capacity, Online tab on the left
  • Select Properties
  • Click on Volumes tab and
  • Confirm the Partition style.

You will see what is loaded in the GUID Partition Table.

Is It Possible to Boot from USB in UEFI Mode?

Yes, you can boot from USB in UEFI mode but in order to do it successfully there are a few specific requirements and steps to follow.

First of all, you must make sure that the hardware of the hard disk supports UEFI. If it does not, you will first have to buy one that supports it.

Also, one of the most important things to make sure is that the system disk is in the GPT or Globally Unique Identifier Partition Table form. If it is not then you will have to convert Master Boot Record or MBR to GPT first.

Now, if both of these conditions are fulfilled, you will need to prepare the USB drive and do a few specific things beforehand.

First of all you will need to create a UEFI bootable USB, and for that you can follow these three steps using a flash drive with 8 GB of space at least.

The first method is to use the Windows Media Creation tool if your computer has a UEFI firmware. The steps to follow are:

  • Connecting the USB flash drive to the computer
  • Clicking on Download Windows Media Creation Tool from the official website of Microsoft
  • Saving the tool in the computer
  • Running it as an administrator
  • Clicking on Accept to agree with the terms and conditions of the license
  • Clicking on Create Installation Media USB flash drive, DVD, or ISO file in the pop-up window
  • Clicking on the Next button
  • Clicking on Use the Recommended Options for This PC
  • Clicking on Next to select the language, architecture and edition of your computer automatically
  • Selecting the USB flash drive option
  • Clicking on Next
  • Selecting the USB flash drive from the list of Removable Drives or from Refresh Drive list
  • Clicking on Next and wait for download to complete
  • Clicking on Next so that creating the Windows 10 bootable USB is created and
  • Clicking on Finish when the screen shows that the USB flash drive is ready.

The second method to create a UEFI boot USB is by using an open-source program, such as Rufus, and an obtainable ISO file. You will need to connect the USB flash drive to your computer system and then follow these steps:

  • Click on download to install the program on your computer
  • Launch it
  • Select the USB flash drive option from the Device menu when the main interface opens
  • Go to the Boot Selection tab
  • Click on the Select button
  • Look for the folder path and select the Windows 10 ISO file from it
  • Select the Standard Windows installation option from the drop down menu of Image options
  • Select the GPT option from the drop down menu of the Partition Scheme
  • Select the non-CSM UEFI option from the drop down menu of Target system
  • Click on Show advanced drive properties section
  • Check default settings
  • Go to the Volume Label field and type a name for the USB drive
  • Select a File system and size of cluster from the drop-down menu
  • Confirm Format options
  • Click on the Start button
  • Click on the OK button
  • Click on the Close button.
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Now, if there is no GPT disk, you need to convert MBR using a reliable partition manager tools and following these steps:

  • Connect the USB flash drive to the computer
  • Download and launch the program to get to its main interface
  • Select the USB drive
  • Click on Convert MBR Disk to GPT Disk option and
  • Click on Apply.

Once it is done you are ready to move Windows 10 to the flash drive by following these easy steps:

  • Select the Migrate OS to SSD/HD feature from the main interface
  • Select the option to copy the system that requires partitions
  • Click on Next
  • Select the USB drive
  • Click on Next
  • Click on Yes on the warning message to confirm destroying the data on the target disk
  • Select the right copy option
  • Click on Next and when done
  • Click on the Finish button and finally
  • Click on Apply.

Now, eventually you can boot your computer system from the migrated Windows 10 from USB in UEFI mode. Here are the steps to follow:

  • Switch on the computer
  • Press F2 keys and the ESC or Delete keys for the Setup utility window to open
  • Press the right arrow key to go to the Boot tab
  • Select the UEFI/BIOS Boot mode
  • Press Enter
  • Select the UEFI Boot Mode in the pop-up window by pressing the up and down arrow keys
  • Press Enter
  • Press F10 key and Enter to save the changes and exit.

Finally, you will need to enable the UEFI boot mode to access the BIOS Setup utility and use it. The steps to follow are:

  • Press F10 and ESC or Delete keys while booting to open the BIOS Setup utility program
  • Go to the Boot tab
  • Use the arrow keys to select the UEFI/BIOS Boot Mode
  • Press Enter
  • Press the up and down arrow keys to select the UEFI Boot Mode
  • Press Enter and
  • Press F10 to save the changes and exit.

After all these steps are done, you will have the system boot up from USB in UEFI mode.

Questions & Answers:

Where is It Stored?

Pretty unlike the Basic Input Output System or BIOS, the UEFI is not stored in firmware but in a directory in a Non Volatile random Access memory or NVRAM.

This means that the UEFI can be stored in the hard drive, or in the NAND flash memory on the motherboard and even on a network share.

What Happens if UEFI Setting is Changed?

Several things can happen when you change the UEFI settings depending on the specific circumstances right from the computer failing to boot up to an increased performance.

Is It Good to Use UEFI?

Yes, it is quite a good feature to use because the newer mode of UEFI comes with much better features and functionalities over and above the security features in comparison to the Legacy BIOS mode.

Can UEFI Increase Performance?

Yes, it can and it is all due to the easy update of BIOS with its features and functionalities which includes faster boot time, discrete driver support, Secure Boot security, better programmability, higher performance, and greater scalability.


UEFI is very important for booting up a system and ensuring faster boot up, more security and reliability.

If your system is running on Legacy BIOS you can change into UEFI with some simple steps, provided the conditions permit, as suggested in this article.

About Puja Chatterjee

Puja ChatterjeePuja Chatterjee is a technical writer with extensive knowledge about computers. She graduated from BIMS. Her expertise includes technology writing and client relationship management gained through over 12 years of experience. Follow Her at Linkedin.

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