U.3 drives are still backward compatible with U.2, thoughthe U.3 drives determine which host type it is inserted into (by using different combinations of H-PT0 and HTP1 being open or ground), and configure the data lanes on power-up. U.3 drives can still act as dual-port NVMe drives in supporting systems.
U.3 is a Tri-mode standard, building on the U.2 spec and using the same SFF-8639 connector. It combines SAS, SATA and NVMe support into a single controller. Where firmware support is available, U.3 can also support hot-swap between the different drives.
The card only work for U.3 SSD, not work for U.2 SSD,not work for SATA/SAS SSD.
This PCI Express card expands the PC by one U.3 SFF-8639 interface.It can be connected e.g. the U.3 U3 PM1735 Series SSD.


