How to Switch from Legacy to UEFI BIOS Mode on Windows 11

[ZevCannon]

Has anyone managed to transition a Windows 11 system from Legacy mode to UEFI mode without having to undergo a full system reinstallation? My current computer is operating on Windows 11, and upon inspection, I discovered that it is configured in Legacy mode. I am interested in switching it to UEFI mode primarily to enhance performance and compatibility. Although I have come across various guides online, they mostly suggest reinstalling the system or indicate that the process is quite intricate. Restarting from scratch is not something I wish to do. 

Has anyone attempted a direct conversion approach? Is this procedure overly complicated? Could you kindly share any specific steps or your personal experience with this transition?

[#2]

@ZevCannon 

Switching from Legacy BIOS to UEFI mode on a Windows 11 system requires several steps. Here’s a detailed guide to help you safely convert your system to UEFI:

Prerequisites:

1. Back up your data: This process involves changing your system boot mode and partition scheme, which can risk data loss. Always create a backup of your important files.
2. Verify UEFI compatibility: Most modern systems support UEFI, but you should check your motherboard specifications to confirm.

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Step 1: Check Your Current BIOS Mode

1. Press Win + R to open the Run dialog.
2. Type msinfo32 and press Enter.
3. In the System Information window, look for the “BIOS Mode” entry:
   • If it says Legacy, you’re in Legacy BIOS mode.
   • If it says UEFI, you're already in UEFI mode and no changes are necessary.

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Step 2: Convert MBR to GPT (Required for UEFI)

To switch from Legacy to UEFI, the disk must use the GUID Partition Table (GPT) instead of the Master Boot Record (MBR). Windows 11 requires GPT for UEFI boot.

1. Open an Administrator Command Prompt or PowerShell:
   • Press Win + X and select Terminal (Admin).
2. Run the following command to check if your disk is already GPT:
   bash

   Copy code

   mbr2gpt /validate
   • This command checks if the disk can be converted to GPT.
   • If it validates successfully, proceed to the next command.
3. Convert the disk from MBR to GPT using the following command:
   bash

   Copy code

   mbr2gpt /convert
   • This process should complete quickly. It will modify the partition style to GPT without affecting the data on the disk.

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Step 3: Change BIOS Settings from Legacy to UEFI

Now that your disk is in GPT format, you can switch the BIOS mode to UEFI:

1. Restart your computer and enter the BIOS setup.
   • Usually, you can access BIOS by pressing a key like F2, Del, Esc, or F10 during the boot process (check your motherboard manual for the correct key).
2. Once in BIOS:
   • Look for Boot Mode or Boot Configuration options.
   • Change Boot Mode from Legacy (or CSM) to UEFI.
3. Save your changes and exit the BIOS.

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Step 4: Boot into Windows 11 in UEFI Mode

1. After saving and exiting the BIOS, your system should restart.
2. If all steps were followed correctly, Windows 11 should boot up in UEFI mode.

Step 5: Verify UEFI Boot

Once logged back into Windows:

1. Press Win + R, type msinfo32, and press Enter.
2. In System Information, confirm that the “BIOS Mode” now shows UEFI.

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Troubleshooting:

• If Windows doesn’t boot after switching to UEFI, re-enter BIOS and ensure that Secure Boot is disabled for initial testing. You can re-enable Secure Boot after verifying that Windows boots properly in UEFI mode.

This should successfully convert your system to UEFI mode.