You can attach it to the onboard SATA (as long as you aren't using SAS drives), but the onboard SATA with RAID enabled is the S100, which doesn't work with 2012 either, so you will need to disable RAID in the BIOS for SATA operation settings. I would probably go this route myself.
OK, for the record, choosing S300 DOES get you a piece of hardware (piece of poop in my case : ) It's not strictly software.Yes, the S300 is a piece of hardware (that does not make it a "hardware" RAID controller) - it uses the system's resources to manage RAID (it does not have a dedicated processor for this).
[/OS managed raid? I heard that's the worst way to go? Performance wise and troubleshooting.Is it ideal? No. In comparison with the performance of a low-end controller though, it is no less flexible in configuration and probably will give you better performance.
so if I had chosen the OS while building the machine on the dell website, it would have balked with the S300?