Need help in changing BIOS settings from legacy boot to UEFI boot.

After running MBR2GPT on my system with a successful completion, I realized that I don't know how to change the BIOS from legacy to UEFI, resulting in the inability to boot the GPT'ed system. I was running Windows 10 Creator on an MBR system using an MSI H61M-E23 (version 2) motherboard. I made the mistake of thinking that setting the boot mode to UEFI would be easy - I tried setting the first boot device to UEFI, but that did not work. The system does not boot - all I get is a blinking cursor. Any help would be appreciated.

Look for a setting to enable/disable CSM mode and disable it.

First, thank you for your quick responses. Unfortunately, neither response provides me with a solution.

There is no CSM mode provided in my version of the BIOS (Aptio setup utility).

The options menu provided for Boot Configuration are: USB Hard Disk, Hard Disk: Sandisk Ultra II, USB CD/DVD, USB floppy, Network, Bev, UEFI, Disabled. I have no choice of 'UEFI-HD/SSD' (1), only 'UEFI'. And I do not have 'UEFI Boot Drive BBS Priorities', instead the only choice I have is 'CD/DVD Rom Drive BBS Priorities'. BTW, when I choose 'UEFI' for 1st boot, at boot, the system flashes the logo and returns to the BIOS's main menu. I have the same version of the Aptio setup utility (version 2.10.1208) and my Bios Version is E7680IMS V10.14.

Even though the MBR2GPT utility presented a successful completion, now I am questioning that. Is there some sort of 'offline' validation of the GPT'ed system that I can perform ??

You can boot the computer from a recovery USB flash drive like Kyhi's recovery tools and we can look at the disk layout.

While waiting for a response, I brought up Diskpart to take a look at the partition layout and noticed when doing a 'detail disk' on the system disk, 'Boot Disk' was flagged as NO in the provided information. I will take your suggestion re Kyhi's recovery USB.

Can I use diskpart to set the EFI partition as active ?????

NavyLCDR said:

Look for a setting to enable/disable CSM mode and disable it.

Hi,
Not an expert as you but disabling CSM I'm pretty sure will make a system not boot anymore :/

This question is for AddRam - I'm not sure what your question addresses. Did I change what ?

As for ThrashZone, The BIOS setup utility does not even mention CSM.

ThrashZone said:

Hi,
Not an expert as you but disabling CSM I'm pretty sure will make a system not boot anymore :/

Disabling CSM mode only disables booting from legacy BIOS MBR partitioned drives. It forces booting in UEFI more only.

And on a GPT drive for UEFI booting, there should be an EFI System Partition that is formatted as FAT32 to boot from, but therr is no active partition.