I want to switch from MBR (BIOS) to GPT (UEFI)

Brink said:

Your GIGABYTE B450 AORUS PRO motherboard specs below show that is does.

I found this in my motherboard's manual (open image in new tab if you can't see the full image)


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I guess that basically means that I just need to disable CSM Support and don't touch anything else after conversion, then it will only boot in UEFI

Brink said:

Please refer to the tutorial below for the exact steps and order to take to avoid disaster.

You would only want to disable CSM after converting to UEFI.

Convert Windows 10 from Legacy BIOS to UEFI without Data Loss

Yeah I will disable it after I convert, thank you anyway

I have been using GIGABYTE and UEFI + GPT. I have never disabled CSM Support, which does not affect booting in UEFI mode.

Matthew Wai said:

I have been using GIGABYTE and UEFI + GPT. I have never disabled CSM Support, which does not affect booting in UEFI mode.

Maybe because you're booting into Legacy and not UEFI

Matthew Wai said:

I have been using GIGABYTE and UEFI + GPT. I have never disabled CSM Support, which does not affect booting in UEFI mode.

ashramnavivi said:

Maybe because you're booting into Legacy and not UEFI

If the drive is GPT partitioned, it is impossible to boot it in Legacy mode.

Booting in Legacy mode is impossible:



I used Linux Mint to convert the disk from MBR into GPT without data loss years ago.

My GIGABYTE manual says the same things as the OP's does.
My understanding is that CSM Support allows booting in both UEFI and Legacy as shown below:



I can boot into Windows 10 in UEFI mode.
I can boot into Linux Mint in Legacy mode.