GPT is modern and has many advantages over MBR. However, there are also some issues with GPT booting in Legacy BIOS mode. GPT is part of the EFI specification, of course it will work best in UEFI mode. But maybe it will not be compatible and can not boot up on the BIOS computer. See more here. Microsoft also does not support booting Windows on a GPT hard disk in Legacy BIOS mode.
So far, MBR is still supported in both UEFI and Legacy BIOS boot. However, there are several reasons that you must use GPT instead of MBR. MBRs only work with disks up to 2TB in size. If you have a hard disk larger than 2TB (e.g. 3TB), use the GPT format to get the full capacity of the disk.
AIO Boot now supports installing Grub2 on GPT disks including both HDD and USB. After installing Grub2, you can boot the GPT disk in Legacy BIOS mode.
Windows Boot Manager does not support booting into Legacy BIOS mode on GPT disks. AIO Boot uses wimboot, which consumes more RAM.
- Install AIO Boot to a partition on GPT disks.
- Grub2 requires a BIOS partition on GPT disks. We will create a small partition of 1 to 10MB. You do not need to format and do not need to mount the drive letter for this partition. For USB, you can use the MiniTool Partition Wizard to create a second partition. On Linux, this partition will be flagged as bios_grub.
- Run AIOCreator.exe, select Grub2 from Bootloaders. The tool will list the partitions that you created in step 2.
- Select the partition and click OK to install Grub2.