MSI B550 Gaming Plus: Blank screen after enabling Secure Boot (already on GPT/UEFI)

[nathanpete15e002e9]

For starters, I have been working through this issue all night with Claude and they just gave up, said go to the MSI forums to ask help, so here I am. I hope somebody here could help. Some of the stuff below is generated by Claude as a summary of what we have already tried. So mods, please don't ban this account for AI generated content, It is I, a human, who an AI was unhelpful for, talking and replying.
So everything below is stuff that Claude suggested I do, and had no success with, and I have come to the forums for some more opinions. I just want to play some BF6 and need Secure Boot to be enabled to do so.
Specs:
- Motherboard: MSI B550 Gaming Plus (Click BIOS 5, updated to latest BIOS)
- GPU: RX 5600 XT (no iGPU available)
- OS: Windows 10
- Boot drive: GPT, UEFI mode

The problem:
When I enable Secure Boot (Standard mode, factory default keys enrolled), I get the MSI splash screen on POST and then a permanent blank screen. The system never boots into Windows. Disabling Secure Boot immediately resolves it.

What I have already verified and ruled out:
- Boot drive is GPT, not MBR
- BIOS is in UEFI mode (confirmed via msinfo32)
- EFI System Partition is present and healthy on Disk 2, Partition 1 (100MB, type: System)
- Full correct partition layout: 100MB System, 16MB Reserved, 930GB Primary, 573MB Recovery
- BCD entries look correct — Windows Boot Manager device is correct, Windows Boot Loader shows path: \WINDOWS\system32\winload.efi and device & osdevice are partition=C:
- RX 5600 XT has full UEFI GOP support so GPU is not the issue
- BIOS has been updated to latest version
- Tried clearing and re-enrolling Secure Boot keys

Things Claude expected to find in my BIOS, but I cannot find:

- No CSM toggle anywhere besides the standard UEFI menu, as a toggle in the bottom right between UEFI and CSM (not under Advanced, not under Boot)

- No "Boot mode select" and no "Windows 10 WHQL Support" option

- No "Above 4G Decoding" (I do have "Above 4G Memory/Crypto Currency Mining" but that appears unrelated)

- The Boot menu only shows boot device priority order and UEFI Hard Disk Drive / USB BBS Priority submenus

- PCI Subsystem Settings only contains: Above 4G Memory, PCI_E1 Max Link Speed, Chipset Gen Switch, PCI_E1 Lanes Configuration

Note: The presence of UEFI BBS Priority menus suggests CSM may be active but not exposed as a toggle on this board.

Has anyone successfully enabled Secure Boot on a B550 Gaming Plus? Is there a hidden CSM setting or a specific BIOS version that works? Any help appreciated. Unfortunately I have to step away from this desktop and get back to work on my laptop, I will be back in a few days to take action on any suggestions and make follow up comments.
Below is a bunch of BIOS screenshots in case that would be easier to read than the bullet points above.

 

[ericj159802e9]

Do the Windows Logs (Event Viewer) give us a clue?

 

[Jarous1]

I don't know how it is today, but Windows definitely didn't like this kind of messing around with turning Secure Boot on and off... Back in the day, if it was installed without Secure Boot enabled, it wouldn't boot up once Secure Boot was turned on. And vice versa. Especially if you're running Windows 10...
The only thing that helped was a complete reinstallation of Windows. Of course, after turning Secure Boot on first...
But as I said, that was back in the day. Today, there might be a way to fix it without reinstalling Windows.

 

[Goodspeed]

The Secure Boot is enabled by default in current AM4 BIOS and earlier versions, so I guess most people don't have issue with it or there would be many complaints.
Re-installing Windows with Secure Boot enabled should be the fastest way to verify it.
Or try to upgrade the latest Windows 11 build and see if it can work.

 

[nathanpete15e002e9]

Do the Windows Logs (Event Viewer) give us a clue?

The event viewer does not give a clue, as it does not ever make it to windows to log anything.

 

[citay]

- RX 5600 XT has full UEFI GOP support so GPU is not the issue

I wouldn't be entirely sure. Some GOP implementations are buggy and require a firmware update (to update the GOP with a newer version). Both NVIDIA and AMD have been plagued by this, NVIDIA released updaters for many of their graphics card series, on AMD you'd have to to it manually, see solution 2) from here.

- OS: Windows 10

Windows 11 is the OS of choice nowadays. There is no excuse to still keep using Win10, support ended in October 2025 (unless you subscribed to Extended Support until October 2026, but even then the countdown is ticking). With two free tools linked here, you can make it look like any Windows, i made it look and feel like Win10.

I highly suggest updating to Win11, maybe it can help solve this. If you happen to have a spare SSD, disconnect your current SSD and do a fresh install of Win11 according to step 3) here.

You can also try a Clear CMOS for the BIOS (shorting the two JBAT1 pins with a screwdriver while the power is removed), to start from scratch in the BIOS.

- No CSM toggle anywhere besides the standard UEFI menu, as a toggle in the bottom right between UEFI and CSM (not under Advanced, not under Boot)

On the last screenshot, "BIOS CSM/UEFI Mode", but you always want to keep this on UEFI nowadays. CSM will just cause trouble down the line.

- No "Boot mode select" and no "Windows 10 WHQL Support" option

They are named as such in newer and older boards, respectively.

- No "Above 4G Decoding" (I do have "Above 4G Memory/Crypto Currency Mining" but that appears unrelated)

No, it's the same thing. Can be named differently on older/newer generation boards. On the latest boards, with certain settings, it's forced to Enabled, you can't even change it. Should always be enabled in UEFI mode.

- The Boot menu only shows boot device priority order and UEFI Hard Disk Drive / USB BBS Priority submenus

Does it list "Windows Boot Manager"? See here.