Question Gigabyte Z370N Wifi Fast Boot Issue

Jul 29, 2019

I recently acquired a new small form factor PC at an exceptionally good deal on Craigslist, and I've added an XPG Gammix 1TB NVMe SSD to the setup in addition to 2x SATA SSD's.

Everything works beautifully and I can boot into Windows except when I enable BIOS Fast Boot in any configuration at all, even with the NVMe SSD (the only Win10 installation present and no USB drives connected) as the only possible boot device, I get the error "Reboot and select proper boot device. etc etc etc"

A fair amount of Googling didn't really help me, as I mostly saw people with boot order problems causing this. I was just curious if anyone has experienced this and understands what's going on?

I have a sneaking suspicion that it may have something to do with USB devices being partially enabled with fast boot, but I'm afraid to turn that off because I don't have a PS2 device to connect if I can't get back into Windows after disabling it. Similarly, if I DID get this working with USB devices disabled, would that cause me to not be able to get into the BIOS if I ever borked my Windows installation for example? I guess I could just reset CMOS if that ever happened.

Overall, this issue isn't really a big deal, I can live with Fast Boot disabled but I wanna understand why this is happening if possible. Any info will be much appreciated! Thanks in advance!