It was labeled UNRAID when I tried it first (and it didn't work). I re-labeled it UNRAID and it works now.
Before this I set up an old HD to boot with UNRAID. I was getting ready to buy a new motherboard and getting pretty frustrated with the whole thing. It took me several hours to get the booting part straightened out, I tried all kinds of motherboard settings and kicker CDs, floppies, etc.