Open the tower and swap drives in "dead" bays into live bays and insure they are working drives.

Edit: Sry.. I see.. you never had drives in those bays. Could it be that the new drives are just not being recognized? Pull the 2 working drives and pop them into the "dead" bays and reboot.

"If it turns out that President Barack Obama can make a deal with the most intransigent, hard-line, unreasonable, totalitarian mullahs in the world but not with Republicans? Maybe he’s not the problem."