The OWC Blog says when the 2012 MacBook Pros were released they found that SATA 3.0 SSDs – such as the OWC Mercury EXTREME Pro 6G and the Mercury Electra 6G – exhibited poor performance and reliability in the 13-inch model when installed in the optical bay via an OWC Data Doubler, while the same SSDs in the 15-inch model worked just fine.
The report notes similarity to what happened in 2011, in which case the 13-inch MBP models were the only ones able to handle their Mercury 6G SSDs in the optical bay at first. Eventually, though, an Apple firmware update resolved the problems in the 15-inch and 17-inch models in the main drive bay.
As it turns out, the same thing happened to the 2012 models, but Apple’s EFI Update 2.9 for MacBook Pro appears to have fixed the problem, so if you have a 13-inch 2012 MacBook Pro and want to install an OWC 6G SSD in your optical bay via a Data Doubler, head over to Software Update and run the EFI Updater.
For the full report visit here: