Stuck in bios after changing from CSM to UEFI

[maidlerev156802d9]

I wanted to turn on secure boot but when I change from CSM to UEFI I get stuck in a bios loop.

 

[polishsirhawk]

MBR2GPT - Windows Deployment

Use MBR2GPT.EXE to convert a disk from the Master Boot Record (MBR) to the GUID Partition Table (GPT) partition style without modifying or deleting data on the disk.

learn.microsoft.com

 

[darkhawk]

I wanted to turn on secure boot but when I change from CSM to UEFI I get stuck in a bios loop.

>>Posting Guide<<

 

[citay]

With the BIOS in the modern more advanced and nowadays preferred UEFI mode, it requires the boot drive to have a so-called GPT. But as your BIOS previously was in the older CSM mode (which was only necessary for an old OS like Win7, or when you re-used a Windows installation from an older system), it will have prepared the boot drive to have a so-called MBR. So you have to do a quick MBR to GPT conversion for the Windows boot drive, then the BIOS in UEFI mode can boot from it again. It takes just a couple minutes to get this going again.

Maybe this is also a good opportunity to update the BIOS to the latest version, because that will (for most halfway newer boards) automatically enable UEFI mode, firmware TPM and Secure Boot, so you are ready for Win11. You will have to do the MBR to GPT conversion either way. Secure Boot is an UEFI function, and for UEFI to boot the OS from the drive, it has to have a GPT.

 

[GhiaOne]

Do you also have to convert a non-bootable data disk when moving OS from MBR to GPT ?

 

[citay]

A GPT is only necessary for the drive that the OS is on, others can have an MBR.

 

[GhiaOne]

A GPT is only necessary for the drive that the OS is on, others can have an MBR.

Thank you ! I have searched the net to find a definitive answer to this, and didn't succeed...