After a power outage, my PC switches back to CSM mode and disables Secure Boot. Every time this happens, I reboot into UEFI/BIOS to fix it by reinstalling the factory default keys, turning off CSM, saving those settings, and enabling Secure Boot again. However, today when I did that, my system booted straight to UEFI and I can't find my boot drive or even my storage drive in the boot options. My PC also isn't detecting the boot drive when I turn CSM back on. The only way I can get into Windows is by disabling both CSM and Secure Boot. I'd really like to keep Secure Boot enabled and avoid reinstalling Windows 11. Any suggestions?
1 Answer
It sounds like there might be an issue with your BIOS settings. Secure Boot requires UEFI, and switching to CSM can make your drive unbootable if Windows was installed under UEFI. This behavior, along with your motherboard resetting after a power outage, suggests there might be a problem with your motherboard's BIOS. First things first, check if the CMOS battery needs replacing—if it’s faulty, that can cause these resets. Try that and see if it helps!
That's strange! The fact that it boots fine in CSM after a reset is puzzling, especially since your SSD is formatted as GPT. Maybe your Windows installation isn't fully compatible with the current setup. Remember that switching from MBR to GPT post-install can cause issues. Just be cautious!

I'll buy a new CMOS battery tomorrow and give it a shot.