No, only a single internal controller is supported. The x24 backplane only has one SASA and SASB set of connections. Those are designed to be connected to a single controller. You may be able to split them between two controllers, but I don't know what the outcome would be. It may not work at all, may work but produce an error, or may work without error. There is no way to use a 3rd controller. The other SAS slot is designed to connect to the x2 rear backplane, not a controller.