Intel Motherboards - Cannot boot from MBR device

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Cannot boot from MBR device

Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=15483
Printed Date: 02 Aug 2025 at 8:57pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com

Topic: Cannot boot from MBR device

Posted By: Lenster45A
Subject: Cannot boot from MBR device
Date Posted: 23 Aug 2020 at 4:15am

Z370 Taichi BIOS 3.40 8700K

I am having a problem when trying to boot from an MBR device whether it is a HD or USB.
The message I get is to select the proper device to boot from and try again.
I can see both entries for the device in the boot selection menu. But the only one I can boot from is UEFI. For example, If I create a Bootable USB using RUFUS and select MBR/UEFI in the creation, I see two entries for the drive but I can only boot from the UEFI entry. I should be able to boot from either.

CSM is enabled in the BIOS. I tried to reflash the BIOS with the same version in case it was corrupted but it would let me.

I know this was working a while back as I was able to install windows in MBR.
mode. The reason I wanted MBR mode was I have three copies of windows on three different drives and select the one I want by F11. I can no longer boot the MBR drives.

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Len