Breaking the SATA Barrier: SATA Express and SFF-8639 Connectors
 

Pretty much all high-end client SSDs have no issues saturating the current 6Gbps SATA interface. We've talked about a move to PCIe based SSDs but these are the connectors that will do it.

On the right you have SATA Express, which will deliver up to 1GB/s on PCIe 2.0 and up to 2GB/s over PCIe 3.0. On the left there's the eventual landing place: the SFF-8639 connector, good for PCIe x4 with speeds of up to 4GB/s (PCIe 3.0).

http://www.anandtech.com/show/6294/b...639-connectors