The Silicon SATA / RAID controller are one and the same. In other words the silicon controller is a SATA controller that also supports RAID. The nVidia controller is the same way. There is a set of Silicon SATA controllers (the red plugs) and a set of nVidia SATA controllers (the black ones). Both SATA controllers support RAID configurations. Therefore if you wish to use RAID configuration on either of the two controllers, that controller must first be enabled or "turned on." You cannot set up RAID (or even use a hard drive) on a controller that is turned off. You can, however, enable the SATA controller but not set up your disks in RAID configuration and thereby not using the RAID feature. RAID capability is a feature or attribute of the SATA controller. . .not a separate controller on its own really. It is analogous to DDR memory in Dual Channel mode. DDR is the type of memory and Dual Channel is the configuration of the memory. Just because your motherboard supports dual channel RAM configuration doesn't mean you have to use it. Likewise, SATA is the kind of drive and RAID is the configuration. You can hook up a plain SATA drive to a RAID enabled controller but not use RAID. Get it?
Now there is one difference. . .with the Silicon SATA controllers, you cannot explicitly disable RAID. If you use the Silicon controller but only a single drive, I believe you will still have to register your single drive as a JBOD array. With the nVidia controller, you can explicitly turn on and off RAID support on each channel.