"The first generation drives used an Intel branded controller with the part number PC29AS21AA and the new second generation drivers use an Intel branded controller with the part number PC29AS21BA0. The controller was changed for a number of reasons, but you can bet that performance and added features is the number one reason for going to a new controller. The new controller architecture still employs the same 10 parallel NAND Flash channels used in the original controller but can now support features like TRIM. Legit Reviews asked Intel if TRIM would ever be supported in the first generation Intel SSDs and they stated that "No TRIM support for 50nm Intel SSD drives is planned at this time". They also went on to inform us that Intel will provide TRIM support on its 34nm High-Performance Solid-State Drives via a firmware update in Q4'09..."