A week after reports first surfaced of a downgrade in SATA bus speeds, Apple has issued a fix that both solves the problem and puts an end to conspiracy theories about it.
The issue centered around new MacBook Pros having a SATA speed of 1.5 gigabits, down from 3 gigabits on previous models, including the low-end MacBook. While there would be no performance degradation on any MacBook Pro with a mechanical hard drive or standard solid-state drive, there was at least a theoretical decline in performance for those with faster SSDs, like the Intel X-25M.
MacBook Pro EFI Firmware Update 1.7 “addresses an issue reported by a small number of customers using drives based on the SATA 3Gbps specification with the June 2009 MacBook Pro.” Interestingly, there is also a caveat: “While this update allows drives to use transfer rates greater than 1.5Gbps, Apple has not qualified or offered these drives for Mac notebooks and their use is unsupported.”
As the owner of a unibody MacBook, I can report that my “unsupported” Intel X-25M has run like lightning for six months and counting. The real issue here isn’t about unsupported drives, but how something like this slipped through Apple QA. Nonetheless, those considering upgrading their drives can now be confident of the best performance, be it real or imagined.