Chosen Solution
I had a SSD in my MacBook Pro 13’’ mid 2012 working for some time, and one day it did not boot anymore, I tried reinstalling the system, recovering from Time Machine, pulling it out and reinstalling OS X on it through a USB case, all to no success. I checked the SmartStatus with DriveDx (through another computer) and it had a huge count of UDMA Errors. I replaced the drive with a HDD and it worked, so I thought that maybe the SSD’s controller went kaput (sent it back to the manufacturer, did not receive any news yet). I bought another SSD (brand new) put it in the MacBook, installed the system and as soon as I booted, started having freezing beach balls all the time. I ran BlackMagic Disk Speed Test and Read/Writes were around 120MB/s, way below what was expected. Put the old HDD back, the computer worked OK, so I thought it was the cable that was damaged, not supporting higher speeds (strange thing is that the old SSD would not install or copy anything onto it). Ordered a new cable, put it in, and here is where things get messy. With the HDD, no problem whatsoever. With the SSD, BlackMagic runs at 480MB/s (expected), but after some time, It starts freezing, I/O error counts sky rocket and if I shut it down and restart, I either get the question mark or the prohibit sign. If I wait long enough, it boots, so it seems that the problem is temperature related. Any clues? Do I still have a faulty cable? Any help or insight is welcome.
I replaced the hard drive cable again. Seems that the one that I ordered and replaced was also faulty…
You have me scratching my head a bit here. Your system has a SATA III (6.0 Gb/s) interface so you should be able to gain the fully bandwidth of your SSD. By chance is your HD a SATA II (3.0 Gb/s) drive? If you can look I up, otherwise give us the make and model info. For now check your systems firmware level. Follow this Apple T/N: About EFI and SMC firmware updates for Intel-based Mac computers.
