Chosen Solution
I just upgraded from my stock HD to a 500gb Samsung860 evo SSD. Install went smoothly some problems with downloading the OS but got it working. Now after about a day of having it in it started to develop some problems, 1 it will be running normally then it will just completely freeze up, which I restart and it gods back to normal. 2. I’ll get a black screen where my pointer is still visible. 3rd I’tll be running normally then I’ll get a folder with a blinking question mark on it.
Replace your hard drive I/R cable. Put pads on either side of the cable as it climbs onto the optical drive to prevent the bottom from touching it. I use 3M extreme mounting tape to do this. For a while last year Apple was replacing this cable for free. \MacBook Pro 13" Unibody Mid 2012 Hard Drive Cable Replacement
