Checking in as a user of the same motherboard. It sounds like you are further along than I am, as I'm just looking at XPEnology at the moment as a possible replacement for FreeNAS (which I have been having a lot of difficulty with SMART reporting errors on perfectly functioning drives). If I run into the same booting problems with XPEnology, I will let you know.
Only thing I can add at this point is you might try also disabling the "netwait" management feature in the BIOS
System is FreeNAS
ASRock Intel Avoton C2750D4I
16GB Kingston ECC
4TB WD Red (x8) RaidZ2
USB Thumbdrive for OS
