Go back into the bios and break the raid array using the raid bios setup feature.
Go to the seagate website and get the utility they have posted to format their drives. Download it, install it and point to the drives you want to format, delete the partition on both drives and opt out of the software, do not format now.
Disk Wizard is what you want In the Utilities
Now move them to the real Raid controller and setup your raid array and format it.