There are 2 controllers on that motherboard, do you have these drives all on the sb850's sata3 bllue connectors? I assume you do.
When installing windows do you load the raid drivers during win7 setup?
You shouold be able to see the array. I just reinstalled windows 2 days ago myself. LOL. Without loading the raid driver windows wont be able to boot.
edit - when you format the array, use MBR and not GPT.