How do I get my Gigabyte Z390 AORUS ELITE and Western Digital HD converted from LEGACY TO UEFI, and MBR to GPT, without losing any data?

Hi, I am Henry and I'd like to help.

You can convert your Gigabyte Z390 AORUS ELITE motherboard and Western Digital HD from Legacy BIOS to UEFI and MBR to GPT without losing data using MBR2GPT.exe, but since you’re having trouble with it, here’s a step-by-step guide to troubleshoot and complete the process.

Before follow these below steps, I recommend backing it up in a separate location to ensure nothing is lost.

Step 1: Validate Your Disk for Conversion

Before converting, check if your disk meets the requirements:

1. Open Command Prompt (Admin) and run: mbr2gpt /validate /disk:0 /allowfullos
2. If validation fails, ensure:

• Your disk has no more than 3 primary partitions.
• BitLocker is disabled.
• Your OS is 64-bit.

Step 2: Convert MBR to GPT

Once validation is successful:

1. Run the conversion command: mbr2gpt /convert /disk:0 /allowfullos
2. If the command fails, try running it from Windows Recovery Mode:

• Restart your PC and enter Advanced Startup Options (Shift + Restart).
• Select Troubleshoot → Advanced Options → Command Prompt.
• Run the conversion command again.

Step 3: Change BIOS Settings to UEFI

After converting the disk:

1. Restart your PC and enter BIOS (Del or F2 during boot).
2. Locate Boot Mode and switch from Legacy to UEFI.
3. Disable CSM (Compatibility Support Module).
4. Enable Secure Boot if required for Windows 11.

Step 4: Verify the Conversion

1. Boot into Windows and open Disk Management (Win + X → Disk Management).
2. Right-click your system disk and select Properties.
3. Under Volumes, check if the partition style is now GPT.

Step 5: Install Windows 11

Now that your system is UEFI-ready:

1. You can download the Windows 11 Installation Assistant from Microsoft.

Let me know if any of these steps work for you.