Defective SATA data cable in Macbook Pro
I have a mid-2012 Macbook Pro (13", MacBookPro9,2) in which I installed an Other World Computing (OWC) SSD early in 2014. It ran beautifully for several months and then one day it would no longer boot. After working with OWC techs for several hours over several days, including swapping in a brand new replacement SSD, the system still would not boot off an internal SSD (but would always boot just fine off the SSD when it was mounted in an external enclosure and would always boot off the original 750 Gb original HDD mounted internally). Although most the symptoms suggested that the issue was with the SSD, I eventually took the machine into an authorized Apple repair depot. After initially denying there was anything wrong with the Mac itself, they replaced the serial ATA cable that connects any internal drive to the motherboard and voila!, problem solved. The system had subsequently been running perfectly for several months until last week. Suddenly the exact same problem arose again. I spent considerably more effort with OWC this time, including yet another replacement SSD, but no luck this time either. Per OWC's tech (GREAT company and people, BTW): "It may be a internal SATA cable. As the internal SATA cable gets older it can start to degrade. It will work just fine with slower drives but when it has a fast SSD attached to it and tries to push the data at the speed of the SSD it just can not do it." It's a mystery to me how a cable can degrade, but nonetheless, I'm off to the Apple repair facility again for yet another cable.
With the above background, I'm posting this message to 1) advise others who may have encountered a similar issue and 2) to determine to what extent others may have experienced the same issue and identified the same solution. Since this is the second cable my system has needed in two years, it'll probably happen yet again in another few months, by which time my Applecare extended warranty will have expired and this problem will start costing me money to fix. I'd like to build a case that this is a design defect worthy of a more permanent fix.
MacBook Pro, OS X Yosemite (10.10.2), 8 Gb RAM, 250Gb SSD