Answer to: replace SSD 15" in retina MBP with Samsung 840 Pro Series MZ-7PD512Coming from someone that has a mSata Conversion to Apple Adapter and a Samsung Pro 950 1tb in my Mid2012 Retina Pro, I can tell you anyone that says msata will be slower has no idea wtf their talking about. I know this thread is old, but I get 550 read 530 write. Up from the 450/400 I had with the stock drive. Stop pushing OWC and Transcend. And stop misleading people. I am a Mac Repair tech and I can tell you, the Interface on the board according to the Board Diagram is a simple proprietary sata connector and nothing more. Sata III @ 6.0 Gbps. This changed in mid 2013 to a PCIe. but still a modified connector proprietary to Apple.