What is the difference between SATA II and SATA III for an SSD drive?
While maximum read and write speeds will vary according to brand, the difference is one of speed and, generally speaking, you can achieve approximately 150 – 200% faster speeds with SATA III than is currently available on SATA II, provided you have the drive connected to a SATA III (6Gb/s) controller (SATA II being restricted to 3Gb/s).
This translates to an increase of around 500+ MB/s vs 200-250 MB/s (on average); read speeds typically running faster than write speeds, but even this has been leveling out as drive manufacturers release more updated firmware for their products.
Using a SATA III drive in a SATA II controller is perfectly fine as they are backwards compatible to the older format, but the speed will be impacted by the lower maximum throughputs available, and usually well below that level also. The theoretical limit of SATA II is around 380MB. Most SATA III drives (as well as SATA II) only get as high as 220-250 MB/s (running on a SATA II controller) so if your system supports SATA III, it’s definitely worth it.
Actually achieving throughputs which take advantage of the increased thresholds depends on how you use your machine, however, but if data-intensive reading and write operations are the norm, you can’t go wrong with SATA III. At least until the next version comes along…
