By AOMEI / Last Updated September 11, 2019

UEFI is the replacement for BIOS

The Recent hardware uses unified extensible firmware interface (UEFI) instead of traditional BIOS. UEFI is now on its way to replacing outdated BIOS, which is over 40 years old. Most of the UEFI computers have enabled Legacy boot mode to be compatible with old systems.

If you are using Windows 7 64-bit, Windows 8/8.1, or Windows 10, you can change Legacy to UEFI mode to get better performance and disk support. In Legacy mode, Windows can only boot from master boot record (MBR) disk that has 2TB size limitwhile UEFI mode works with GUID partition table that allows you to use disks of enormous size.

Is it necessary to reinstall Windows 10/8/7 for UEFI mode?

Normally, you need to reinstall Windows for changing to UEFI mode because you need towipe the hard driveand then convert to GPT disk.

1. After you convert Legacy BIOS to UEFI boot mode, you can boot your computer from a Windows installation disk.

2. At Windows Setup screen, press Shift + F10 to open a command prompt.

3. Type “diskpart” and use command “convert gpt” to convert the disk from MBR to GPT as the screenshot below.

Convert GPT

4.Then you can go back to install Windows. If you try to install Windows without these steps, you will get an error “Windows cannot be installed to this disk” after you change BIOS to UEFI mode.

Actually, you do not have to go through all that.

You can use third party software AOMEI Partition Assistant Professional to convert MBR to GPT without any data loss. In this way, you don’t need to spend time installing Windows and programs.

To convert to GPT disk with AOMEI Partition Assistant Professional:

1. Download this partition manager software Demo Vesion and run it.

2. Right click on the system disk and select Convert to GPT Disk.

Convert System Disk to GPT

3. Click “Apply” to apply the change.

Apply to GPT System Disk

In the process, your computer will reboot into AOMEI Pre-OS mode. When it completes, you can go to BIOS and then convert Legacy to UEFI mode. By the way, you can use the same way to convert GPT to MBR without data loss.

How to Change Legacy to UEFI?

From computers to computers, the steps to turn on UEFI mode is different. You can refer to the following to configure it.

1. Continuously press a specific key to enter EFI Setup at computer startup. Usually, it is Del for desktops and F2 for laptops. If you do not know which key to press, just press Esc. It will give you the full menu, and then you can select BIOS Setup.

2. Generally, you can find the Legacy/UEFI boot mode configuration under Boot tab. From there, disable Legacy and enable UEFI.


3. Press F10 to save settings and then exit.

In conclusion, it is recommended to change Legacy to UEFI boot mode as long as your operating system (OS) is compatible with it. As you can see, the whole process won’t take much effort since you don’t really need to reinstall Windows 10/8/7.