Help - my PC can't boot after changing "Windows 8/10 Features" BIOS setting

[milleniumaire]

I have a custom built Windows 10 PC using a Gigabyte AORUS GA-Z270X Gaming 7 1151 7th Gen DDR4 RGB Fusion motherboard.

Stupidly, I tried to change my BIOS settings to prepare for Windows 11 and I now regret it as my PC won't boot.  Two issues were reported by the Windows 11 Update check, both of which required BIOS changes to fix;

TPM
Secure Boot

I managed to Enable TPM without issue, but in order to turn on Secure Boot, it was necessary for me to change the BIOS "Windows 8/10 Features" option from the original setting "Other OS", to "Windows 8/10" in order to then disable "CSM Support".

After saving these BIOS settings and rebooting I got the following message:

"Reboot and Select proper Boot device
 or Insert Boot Media in selected Boot device and press a key"

I tried changing the settings back, so CSM Support was Enabled and Windows 8/10 Features was set to Other OS.  Saved and restarted, but still get the message above.

It would appear that BIOS no longer recognises the M.2 drive in my desktop PC.

I have considered booting from a Windows 10 repair disc, but don't want to do this without being sure there isn't a better way to recover the PC.  I would also like to understand what has happened as there are many websites/videos showing this method of setting Secure Boot with no mention of the potential disaster that may occur.

Any help would be much appreciated.

[dmdilks]

What you can try is setup the bios to the default setting. Plus have you tried to set the 1st boot to the windows boot manager. One other thing is that windows 11 might not support a 7th gen CPU too.

https://www.pcworld.com/article/394793/what-cpus-can-run-windows-11.html

[shadowsports]

What you can try is setup the bios to the default setting. Plus have you tried to set the 1st boot to the windows boot manager. One other thing is that windows 11 might not support a 7th gen CPU too.

https://www.pcworld.com/article/394793/what-cpus-can-run-windows-11.html

Greetings,
I read (somewhere) last week that MS was pulling its CPU requirement, but that some features might not be supported depending on age and which you have.  Of course (as we know) all of this is subject to change.    Here today, gone tomorrow 

@milleniumaire.  Do as dmdilks states.  Load set up defaults and set your m.2 as first boot device.  F10 to save again and it should be able to start.

Note, is your boot drive formatted MBR or GPT?  (this is likely the problem)  You cannot boot UEFI mode with CSM disabled to a disk formatted MBR partition style. 

If you plan to install windows 11 and are using MBR, this might be a good time to perform a fresh install of W11 to a newly formatted GPT partition style disk..  (UEFI only, CSM disabled and Secure Boot)

You can convert MBR to GPT leaving the OS intact (in theory anyway, but I haven't tried it).  Make a full disk image back up before you start experimenting.

This might help:

https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10#convert_mbr_gpt_windows10

Do it in offline mode in the Recovery Environment. 

[shadowsports]

Just a quick update.  MS has not pulled the minumum CPU requirement.  I just ran the W11 Compatibility checker on a TPM 2.0 capable laptop.  Its 100% compliant except for its CPU.  i7-6500U.  Not surprised.