I've got a motherboard that has a couple SATA 6Gb/s connectors (as well as half a dozen SATA 3Gb/s). I have an SSD (this one) that says it's SATA II, which I take to mean for use with 3Gb/s connectors. I've heard that the speeds of many SSDs are "saturating" the throughput of SATA II. What I am wondering is, if I plugged it into a SATA 6Gb instead, would I see higher read/write speeds? Or does the performance of a SATA II SSD not ever exceed the limitations of SATA 3Gb/s?
Current SSDs aren't quite up to the 3Gbit/sec SATA rate yet, and if the drive itself uses a SATA Version 2.0 chipset then plugging it into a 6Gbit/sec SATA Version 3.0 port won't give you any better performance.
So the long and short of it is that it's going to perform exactly the same no matter which port you plug it into.