I would start by updating the server to current. That will be the BIOS, the BMC, as well as the raid controller. If you let me know which controller is installed, I can provide the link. Likely the issue is that the controller is out of date. Let me know.
The only way to fix this problem is to purchase Dell-certified versions of the drive - one that is designed specifically to work with the Dell controllers, not programmed with generic retail firmware. Usually there will be no problem with generic SAS drives, but you will never get rid of the unsupported message for them.