Gigabyte B450M Gaming, black screen on boot after enabling secure boot.

Understanding and Troubleshooting Black Screen Issues After Enabling Secure Boot on Gigabyte B450M Gaming Motherboards

Introduction

Building a stable and secure PC environment involves navigating various BIOS settings, especially when transitioning between different disk formats (MBR to GPT) and operating systems, such as upgrading from Windows 10 to Windows 11. However, users sometimes encounter boot issues, including black screens, particularly after enabling security features like Secure Boot. This article aims to provide a comprehensive overview of such challenges, using a real-world case involving a Gigabyte B450M Gaming motherboard, and offers practical troubleshooting guidance.

Case Overview

A user recently upgraded their motherboard to a Gigabyte B450M Gaming model. Initial setup involved installing Windows 10 on an MBR-formatted drive, which was converted to GPT using Windows’ built-in MBR2GPT tool. Initially, the system operated smoothly with CSM enabled and Secure Boot disabled. Following a series of BIOS adjustments—namely disabling CSM, enabling UEFI mode, and subsequently enabling Secure Boot—the user experienced a critical failure upon installing Windows 11: a persistent black screen on boot, with no response from peripherals or POST procedures.

Key Events & Troubleshooting Steps Undertaken

1. Disk Format Conversion & BIOS Configuration
2. Successfully converted the drive from MBR to GPT.
3. Changed BIOS setting from CSM to UEFI mode.

4. Enabled Secure Boot, restored default keys, and verified that Secure Boot was active via system information.

5. Attempted Upgrades & Resultant Failure

6. Upgraded to Windows 11, which triggered the system black screen upon restart.

7. Tried multiple troubleshooting techniques:

   • Reinstalling and reseating CPU.
   • Clearing CMOS via reset pins and removing BIOS batteries.
   • Removing and re-inserting RAM modules individually.
   • Disconnecting GPU and other peripherals.
   • Power cycling and BIOS resets.

8. Persistent Black Screen Issues

9. Despite thorough hardware resets and component checks, the PC remains stuck at a black screen, with no POST signals.
10. The system does not turn off normally; powering off requires unplugging the power cord.
11. The motherboard remains under warranty, but local availability of replacement Motherboards is limited.

Understanding the Underlying Causes

Such issues often stem from incompatibilities or misconfigurations relating to Secure Boot, UEFI settings, and hardware compatibility. Specific to Gigabyte B450 series boards, known issues include: