No changes, except a recent upgrade to windows 10.
F9 was released in 2012. How log ago did you flash to this rev?
I assume you are running single disks with Z77 Controller Operate Mode set > AHCI ?
Is the boot order correct?
Are other BIOS settings being retained, Date /Time, etc?
Have you tried CLR_CMOS or battery pull? See page 26 of your manual, *disconnect power first
Are there any steps that will allow you to boot into the OS, or do you always get "No Boot Drive Detected after POST?
Sorry for all the questions.