My MB only support SATA 2 (i.e. 3Gbit/s). Im thinking of buying 1 more Hdd. Is Sata 3 (i.e. 6Gbit/s) is backwards compatible? Can I use a Sata 3 hdd on a Sata 2 MB? If possible, I'd like to get a Sata 3 to future proof my rig.
Well, the drive might hit the 3Gb/s mark momentarily-- long enough to fill (or empty) the buffer, but then, it will drop down from there because, as you say, the physical drive can't get anywhere near a 3Gb/s transfer rate to/from media.