Should MCT have an GPT/UEFI option for newer BIOSes

PhilB · May 25, 2026

So I'm doing a fresh install on my system, first since i upgraded to an MSI X870E Carbon. The BIOS would not recognize the thumb drive until I found a post "somewhere" that said that the installer USB had to be GPT/UEFI. Duuh.

Fortunately this is done easily using Minitool Partition Wizard. I get why GPT is better than MBR. I have set up my system to be GPT-drives only.

Is Microsoft behind the times here?

zbook · May 25, 2026

A Windows 11 MCT creates a UEFI / GPT bootable flash drive.

Rufus can create a Windows 11 MCT UEFI with CSM bootable flash drive.

This is an AI chart:

Media Type	Partition Style	Boot Mode	BIOS Compatibility	Notes
Media Creation Tool USB	GPT	UEFI only	No Legacy BIOS	Official Microsoft method
ISO written with Rufus (GPT)	GPT	UEFI	No Legacy BIOS	Recommended for Windows 11
ISO written with Rufus (MBR)	MBR	BIOS/UEFI‑CSM	✔ Legacy BIOS	Requires bypassing Win11 requirements

Celery · May 26, 2026

The Media Creation Tool automatically creates a Windows 11 installation USB flash drive (or ISO file) that is bootable in both BIOS and UEFI modes.

Google Gemini:

Why it is correct

USB Drive Behavior: The Media Creation Tool (MCT) formats the USB drive using a FAT32 file system and sets up the boot loaders so that it can boot on both legacy BIOS (using the Master Boot Record) and modern UEFI systems.

ISO File Capability: The resulting ISO file contains the necessary boot images (etfsboot.com for BIOS and efisys.bin for UEFI), allowing it to be burned or mounted for either environment.

The technical nuances (Why someone might correct you)

Windows 11 System Requirements: Officially, Windows 11 strictly requires UEFI with Secure Boot and does not support legacy BIOS. While the installer itself can technically boot in BIOS mode, the Windows 11 setup will block the installation on the hardware check screen if it detects a legacy BIOS environment.

ISO Burning Tools: While the ISO itself supports both modes, how it boots ultimately depends on the tool the user uses to burn it. For example, if a user uses Rufus, they must explicitly choose whether they want the partition scheme to be MBR (BIOS) or GPT (UEFI).

cereberus · May 26, 2026

echo2446 said:
It's probably due to legacy BIOS/MBR support — the user needs to know they need a GPT-formatted thumb drive for their UEFI firmware.

Rhis is incorrect - the mct installer can hand mbr or gpt. The important factor is how the hard drive is initially formatted.

Celery · May 26, 2026

MPG X870E CARBON WIFI

The MSI UEFI BIOS uses UEFI as the default boot mode to take full advantage of the new chipset’s capabilities. However, it still has a CSM (Compatibility Support Module) mode to be compatible with older devices. That allows you to replace legacy devices with UEFI compatible devices during the transition.

On modern motherboards, the CSM (Compatibility Support Module) is either disabled by default (e.g. on X870E motherboards) or not included at all (e.g. on Z890 motherboards).

CSM (Compatibility Support Module)
- Enabled: Both legacy BIOS and UEFI boot modes are available.
- Disabled: Only UEFI boot mode is available.

When CSM is disabled, the Windows installation USB flash drive appears in the one-time boot menu (ASRock F11, Asus F8, Gigabyte F12, MSI F11) and boot priority settings only with the "UEFI" prefix; this means booting in BIOS mode is no longer an option.

Windows Setup automatically targets the required partition style (GPT for UEFI or MBR for BIOS) based on the mode in which the Windows installation USB flash drive was booted.

garlin · May 26, 2026

Celery said:
Windows Setup automatically targets the required partition style (GPT for UEFI or MBR for BIOS) based on the mode in which the Windows installation USB flash drive was booted.

WinPE knows how it was booted (UEFI vs BIOS).

Back in the W10 days, you could write a custom WinPE script which could run a different set of diskpart commands for a GPT vs. MBR layout.

Code:

wpeutil UpdateBootInfo
for /f "tokens=2* delims=        " %%A in ('reg query HKLM\System\CurrentControlSet\Control /v PEFIRMWAREType') do set FIRMWARE=%%B

if %FIRMWARE%==0x1 (
    echo MBR
) else (
    echo GPT
)

BrianInEngland · May 26, 2026

I have an 8GB partition on an NVMe drive, I boot from that.
USB drives are soooo behind the times!

MSI boards (and likely others) can boot from an NTFS formatted drive.

wabbit · May 26, 2026

BrianInEngland said:
I have an 8GB partition on an NVMe drive, I boot from that.
USB drives are soooo behind the times!

MSI boards (and likely others) can boot from an NTFS formatted drive.

I have a Geekom mini-PC and a Dell Inspiron desktop that can boot from NTFS formatted USB drives using the GPT partition scheme. Geekom recommends creating the install media with NTFS. The windows 11 iso's have had the install.wim file in excess of 4 GB, in which that would need to be split to work on FAT32 druives. The MCT will split the install.wim into swm files and format the usb to FAT32 when making the usb. Downloading the iso through MCT has an install.esd file, also more than 4 GB.

spapakons · May 26, 2026

Celery said:
The Media Creation Tool automatically creates a Windows 11 installation USB flash drive (or ISO file) that is bootable in both BIOS and UEFI modes.

Google Gemini:

Maybe I am doing something wrong, but I don't remember successfully creating a USB flash drive with MCT that boots both in UEFI mode and CSM. So to be extra sure I always create it with Rufus and explicitly select UEFI or CSM depending on target system. Yes, I have two USBs, one UEFI and one legacy.

PS: My system is legacy and this might affect how MCT creates the USB.

bikemanAMD · May 26, 2026

I've been creating with Rufus over the last year or so, but i could always create offically with Microsoft Creation tool, as i did with the Original Windows 11 release in October 2021, and used that for a clean install on my older system back then. That system was UEFI GPT boot, no CSM. worked fine back then at the time.

I jumped onto Windows 11 as soon as it released back then, like i do with all new Operating system releases

spapakons · May 26, 2026

That makes sense. My unsupported computer has a Legacy BIOS installation, so the USB produced by MCT boots in CSM legacy mode but has problem booting in UEFI mode. To make sure it works in UEFI systems, I use Rufus and make sure I select GPT (UEFI). This never fails, but unfortunately it doesn't boot in Legacy BIOS systems.

PhilB · May 26, 2026

cereberus said:
Rhis is incorrect - the mct installer can hand mbr or gpt. The important factor is how the hard drive is initially formatted.

Do you mean the installer thumb drive? MCT formats that as MBR/FAT32.

PhilB · May 26, 2026

echo2446 said:
It's probably due to legacy BIOS/MBR support — the user needs to know they need a GPT-formatted thumb drive for their UEFI firmware.

is that a reasonable assumption? I didn't know that until after I did a search. I am pretty technical, but not exactly in the same league as @garlin and the others in his league.

PhilB · May 26, 2026

zbook said:
A Windows 11 MCT creates a UEFI / GPT bootable flash drive.

Rufus can create a Windows 11 MCT UEFI with CSM bootable flash drive.

I have used Rufus, but I don't need to bypass Win 11 requirements, etc. And using Rufus is an extra step.

PhilB · May 26, 2026

Celery said:
MPG X870E CARBON WIFI

On modern motherboards, the CSM (Compatibility Support Module) is either disabled by default (e.g. on X870E motherboards) or not included at all (e.g. on Z890 motherboards).

My situation here.

Celery said:
When CSM is disabled, the Windows installation USB flash drive appears in the one-time boot menu (ASRock F11, Asus F8, Gigabyte F12, MSI F11) and boot priority settings only with the "UEFI" prefix; this means booting in BIOS mode is no longer an option.

Do you mean "booting in CSM"...?

Celery said:
Windows Setup automatically targets the required partition style (GPT for UEFI or MBR for BIOS) based on the mode in which the Windows installation USB flash drive was booted.

OK. However, I used the MCT on a different system and checked the box for a "different system."

PhilB · May 26, 2026

BrianInEngland said:
I have an 8GB partition on an NVMe drive, I boot from that.
USB drives are soooo behind the times!

MSI boards (and likely others) can boot from an NTFS formatted drive.

So you create the installation files on a spare partition on your NMVe drive? If my MSI board would work like that, I would carve out an 8 GB partition for just that purpose. However, in my current situation, I can't run MCT on my desktop system because the NMVe drive is completely unformatted. Chicken and egg?

zbook · May 26, 2026

The post reminded me that kari had a dilemma and work around for Windows 10.

Maybe some step(s) is/are useful

Clean Install Windows 10 without DVD or USB Flash Drive

How to Clean Install Windows 10 without any External Installation Media

www.tenforums.com

Celery · May 26, 2026

x509 said:
Do you mean "booting in CSM"...?

Booting from a USB flash drive in BIOS mode, Legacy mode, Legacy BIOS mode, or CSM mode essentially means the same thing. In that case, Windows Setup will install Windows using the MBR partition style on the SSD.

x509 said:
OK. However, I used the MCT on a different system and checked the box for a "different system."

Regardless of whether the "Use the recommended options for this PC" box is checked, the Media Creation Tool automatically creates a Windows 11 installation USB flash drive (or ISO file) that is bootable in both BIOS and UEFI modes.

I created a Windows 11 installation USB flash drive with the MCT and verified that this is still true.

Neither of my newer computers supports booting from USB in BIOS mode, but I also have an older laptop that supports both BIOS and UEFI boot modes (see image below). I bypass the Windows 11 system requirements using a .reg file copied to the USB flash drive.

Image below: BIOS boot mode. The "Create Partition" option created an MBR partition table on the SSD. The 100 MB partition is the System partition (the "System Reserved" label is no longer there).

Image below: UEFI boot mode. The "Create Partition" option created a GPT partition table on the SSD. The 200 MB partition is the EFI system partition.

Megahertz · May 27, 2026

What defines the installation (Legacy - MBR or UEFI - GPT) is the way you boot the Win 11 USB installation drive.

Reset BIOS or load defaults.
Set Disk mode to AHCI, not RAID
Select OS mode = UEFI
Disable fast boot and secure boot (you can turn it on after installation)

Windows can be installed in two ways: Legacy-MBR or UEFI-GPT
To install as Legacy-MBR you must boot the installation drive as Legacy
To install as UEFI-GPT you must boot the installation drive as UEFI.

As you have a UEFI BIOS, you should install as UEFI-GPT
Detach any other boot able drives from the MB.

During POST, press F12(?) to launch the boot menu. You will see two options for the USB drive. USB UEFI (Name) and USB (Name). Select USB UEFI (Name) if you want to install as UEFI-GPT or select USB (name) if you want to install as Legacy-MBR.
Go to install and delete ALL partitions on the main drive till you have one and only one unallocated space and then proceed.

Should MCT have an GPT/UEFI option for newer BIOSes

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