Switch from Legacy BIOS to UEFI, MBR to GPT

[Sookite]

Switch Legacy to UEFI. I want to convert my boot SSD (Samsung 512 GB) from MBR partition to GPT using Microsoft's MBR2GPT tool, switching firmware modes from Legacy BIOS to UEFI. Can I accomplish the switch to UEFI simply by enabling Secure Boot and disabling Legacy Support in the Secure Boot Configuration Menu of the HP BIOS setup utility? Will the system automatically boot from the newly converted SSD? If not, what else do I need to do? Thanks.

Windows 10 Home v.1909 build 18363.535. System board 839F 1.0; Sys BIOS F.21

[Grzwacz]

Greetings,

Welcome to the forum.

I am not a HP employee.

Secure boot and Legacy support don't affect the disk partitioning method (GPT vs MBR).

Your PC should have shipped from HP using GPT. Secure boot should also be enabled but you can enable Legacy support and still use GPT. Or you can use MBR when using Secure boot.

How are you determining the OS disk is using MBR?

You can look at Disk Management to check for GPT or MBR. Your PC should have a EFI System Partition on the operating system disk if HP has used GPT.

Enter Disk Management in search then select create and format hard disk partitions to check the current disk partitioning method.

Regards

[Sookite]

Hi Grzwacz, thanks for your response. From Disk Management: Partition Style: Master Boot Record (MBR). In System Information: BIOS Mode: Legacy.

According to the lit Microsoft's MBR2GPT.exe tool converts disks from MBR partition to GPT and configures system partition for UEFI boot. It doesn't support configuring firmware mode. Switching firmware to UEFI mode requires manual configuration in the firmware menu.

Microsoft's doc and a video is here: https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt

In my HP Setup Utility menu, Storage, Boot Order, UEFI Boot Sources list only OS Boot Manager, USB floppy/cd, USB hd.

Legacy Boot Sources include the m.2 Samsung boot SSD and 3TB SATA1 hard drive.

MS warns that after using MBR2GPT to convert the boot disk to GPT partition the firmware has to be reconfigured to boot in UEFI mode.

So I want to be clear on how to switch to UEFI. In my HP Setup Utility Menu, Storage Boot Order, if I Disable Legacy Boot Sources could I be disabling the Samsung SSD and brick the system?  In the Security Menu, Secure Boot Configuration if I Disable Legacy Support and Enable Secure Boot would that complete the switch to UEFI/GPT, or disable the boot disk?

Thanks again for your help.

[Grzwacz]

Hi Sookite,

You're very welcome.

I am surprised to see MBR used on a 2017 PC having a UEFI BIOS. I have worked on 2014 HP PCs which shipped using GPT.

All I can tell you is Secure boot and Legacy support have nothing to do with disk partitioning. Secure boot prevents unsigned hardware code or other unsigned code from running and can enforce specific hardware keys implemented by the MB OEM.

Legacy mode allows unsigned hardware or other unsigned code to run at boot.

These two settings (Secure boot-Legacy support) usually have to be changed when you install certain types of new hardware or install an unsigned non Microsoft operating system.

I am not sure what your problem is or if you have a problem.

Again, I don't know why your OS disk is using MBR to begin with.

Regards

[Sookite]

Hi Grzwacz, thanks again for your response. This is proving to be an oddly perplexing situation. I thought someone would've had experience with Microsoft's MRB2GPT tool and completed a transition from Legacy BIOS to UEFI, MRB to GPT. There are YouTube videos on the process, but the systems used are somewhat different than mine, so I thought I'd query the HP community specifically. You're the only one responding (thanks!) and nobody seems to have heard of MRB2GPT. Maybe I'll post a question about it specifically.

Maybe the simplest question is: How do you switch from Legacy BIOS to UEFI? If you think of anything I'd appreciate hearing from you. Take care.

[Grzwacz]

Hi Sookite,

You're very welcome.

Sounds good, try a new post.

I am aware of this Microsoft tool.

Check this (Link) for instructions and prerequisites to use this tool and accomplish the task.

Your PC has a UEFI BIOS so this process should work.

Again, Secure boot and Legacy support should not affect this task.

But keep the BIOS in Secure boot mode.

Regards

[MRFSYS · Accepted solution]

Here, Julia's YouTube video uses an HP laptop:

She DISABLES "Legacy Support" and ENABLES "Secure Boot":

https://www.youtube.com/watch?v=6ws1viKwckY

Convert MBR to GPT on Windows 10 without reinstalling Windows!

We've been very slow to migrate to Windows 10

(too many serious problems with FORCED Windows Updates).

We've been buying refurbished HP workstations, and

that hardware has been very satisfactory for the

goal of "taming" Windows 10.

The first thing we usually do is to "Migrate OS" using Partition Wizard

to a 6G SSD like the Samsung 860 Pro or Samsung 860 EVO

wired to the SATA0 port on the motherboard.  That allows us

to disconnect the OEM HDD and keep it safe, in case  we

need to "start over".

Our next major project is to try "Migrating OS" using Partition Wizard

from an OEM HDD that comes with a refurbished HP Z220 workstation,

to a Highpoint SSD7103.  The latter requires UEFI booting support

and a PCIe 3.0 x16 slot, and the motherboard BIOS does not need

a "bifurcation" option (x4x4x4x4).

If we can't boot from the SSD7103, we may need to be satisfied

using it for dedicated data partitions, and continue booting

from a JBOD SSD after "Migrating OS" to the 6G SSD on the SATA0 port.

When our experimentation is finished, we'll probably re-connect

the OEM HDD and use it for archive storage.  Along the way,

we always create working drive images at key points in this

development sequence, to ensure recovery to a working system.