I have seen a few threads about possibly some issues once a samsung 850 evo is installed you can't upgrade the firmware in a macbook. Do I need to even worry about this? I also want to do a fresh install of El Capitan and then transfer back my documents/ file, pictures, e-mails from my time machine backup. Is this pretty easy to do? If I did a fresh install of El Capitan do I have to enable trim or does it do it automatically with the install? First time I have tried anything like this with my mac. Trying to make sure i do it right so I don't have any issues. I have a 2012 Classic Macbook pro mid 2012 with I7 AND 8GB's of ram. 750 hard drive. The Samsung is a 1tb.