2012 MacBook Pro 13" NON-Retina. The computer has been running dreadfully slow on 5400RPM HDD so I decided to upgrade to SSD. I installed the SSD; however, The system won't recognize the drive. I tried another drive, and still no luck. Makes me wonder if the seriously slow performance and the two HDDs not coming up is because of a bad HDD cable? I did some searching online, and seems like a common problem.