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

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.

Your system is probably a Legacy-MBR and now BIOS is set as UEFI-GPT.
Try to go back to Other OS, boot into Windows and post a Disk manager image. Don't forget to expand the columns so we can read them.
How to Post a Screenshot of Disk Management

Megahertz said:

Your system is probably a Legacy-MBR and now BIOS is set as UEFI-GPT.
Try to go back to Other OS, boot into Windows and post a Disk manager image. Don't forget to expand the columns so we can read them.
How to Post a Screenshot of Disk Management

They cant. Highlighted the appropriate part below

milleniumaire said:

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.

I have already tried putting the settings back to what they originally were, but it makes no difference and the PC appears to have "lost" the M.2 drive, which contains the OS.

I've been looking through all the BIOS settings, but nothing jumps out as being required to be changed to allow the M.2 drive to be detected.

It makes me wonder if something has been changed on the M.2 drive, which now makes it appear to not have an OS installed, although I wouldn't have thought that should matter to BIOS. I can see my DVD drive and "MultipleCard Reader" neither of which have accessible OS's.

I think I need to figure out how to get my M.2 drive available to the BIOS again, but not sure how.

Look in your boot priority list. Make sure the M.2 drive itself is set to the first priority and not a UEFI OS.

The M.2 drive isn't shown in the boot priority list. This list only shows:

Boot Option Priorities
Boot Option #1 PO: HL-DT-ST BD-RE BH10LS38
Boot Option #2 MultipleCard Reader 1.00


I've just tried booting from my Windows 10 disc to perform a Repair, but it doesn't find any OS's!

There should be a CMOS clear jumper or button to reset BIOS back to defaults. Try doing that reset.

NavyLCDR said:

There should be a CMOS clear jumper or button to reset BIOS back to defaults. Try doing that reset.

Did you converted the drive from MBR to GPT?

A BIOS reset will set it to Other OS and probably it will work.
Start the computer and during POST launch a Boot menu (F12). What are the options on the boot menu?

Megahertz said:

Did you converted the drive from MBR to GPT?

A BIOS reset will set it to Other OS and probably it will work.
Start the computer and during POST launch a Boot menu (F12). What are the options on the boot menu?

No, I didn't convert anything. I'm not sure if I had previously converted from MBR to GPT (a few years ago) as this PC has been running for around 4 years without issue.

I have tried using the BIOS option to reset defaults and I can see it did reset some of them, but it still makes no difference.

I had already changed the setting back to Other OS and it still doesn't work.

The Boot Menu shows the same options as BIOS (see my earlier post). None of these are the M.2 drive!

- - - Updated - - -

Thanks for the help guys, I think I've got it working again and will post a full update of what I did tomorrow as I'm feeling pretty tired now after spending around 5 hours troubleshooting this issue!

milleniumaire said:

Thanks for the help guys, I think I've got it working again and will post a full update of what I did tomorrow as I'm feeling pretty tired now after spending around 5 hours troubleshooting this issue!

Good you have it working again.
Post a disk manager image so we can see what you have.
How to Post a Screenshot of Disk Management