https://forum.asrock.com/ Copyright (c) 2006-2013 Web Wiz Forums - All Rights Reserved. Sun, 05 Apr 2026 01:32:05 +0000 Sun, 23 Aug 2020 04:15:39 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.04 360 https://forum.asrock.com/RSS_post_feed.asp?TID=15483 https://forum.asrock.com/forum_images/web_wiz_forums_black.png https://forum.asrock.com/ https://forum.asrock.com/forum_posts.asp?TID=15483&PID=78429&title=cannot-boot-from-mbr-device#78429 Author: Lenster45A
Subject: 15483
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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