Haven't been on these forums in a really long time, but I'm having quite an ordeal with my 13" Early 2011 MBP. I was using my Mac last night, and all of a sudden it stopped responding. I think to myself, "Well, that's inconvenient," but I proceed to hold down the power button so it turns off so I can turn it back on again. I turn it back on, the Apple logo does not come up, and I get the ol' question mark folder. Great, my hard drive isn't being recognized. I restart it again, holding down the option key this time so I can access the System Startup Manager, or whatever it's called. Thinking I can just select the drive once it appears, the only option available was "Internet Recovery" and my drive was nowhere to be found. Knowing what internet recovery does, I didn't choose the option. Figuring it was either the hard drive cable or hard drive itself that was causing the issue, I shut it down again, and opened up my MBP to "inspect." I've had an issue similar to this before, and when I took it to Apple, they determined it was a HD cable issue, so I paid them to replace that, and thinking it was an issue with the HD, I had purchased a 1 TB HD- so in addition to replacing the cable they installed my new HD as well. This means that I have the original 320GB hard drive that shipped with my Mac, it's contents exactly the way I left it before I upgraded. I pulled out my 1TB HD, put in the old one, and after a few startups, the old HD surprisingly worked, and my computer booted up again. At this point, I assumed it was the 1TB HD that was the issue but since then, I have encountered problems which lead me to believe this might not be all there is to it. After booting up with my old original HD, I removed it again just to see if by any chance the 1TB HD that I was using worked. Unfortunately, it didn't boot up, but I could hear and feel the HD spin. This leads me to my first and second question: If a hard drive is dead, can it still spin? The HD cable is obviously supplying power to both drives I have used, but can it still supply power while being damaged in the data transfer aspect of the cable? I put the old HD back in, and it worked. But, as I've been using it, I've been noticing really slow behavior every now and then, particularly when waking from sleep sometimes, it either does it really slow, or I have to restart it completely, and it can't even find the drive at all. Sometimes, when I turn it on, I get the question mark screen, or sometimes it starts to boot but I get the x-out symbol. Sometimes, to get it to turn on, I have to restart it multiple times, or boot into the startup manager screen, where the drive is recognized sometimes, and other times not. At this point, I'm extremely frustrated. I thought it was the HD, but now it may be a HD cable issue. I've ordered one of those enclosures you can put your internal HD in and hook it up to a computer via USB and it should be here within the next two days. I think I would be correct in assuming that (this is where I also need your expertise: If the hard drive works inside the USB enclosure, it is safe to assume that the problem is not with the HD, but with the hard drive cable. If the hard drive does not work, the problem is with the HD, but the cable could also be screwed up as well. I'm firm on the fact that I'm not going to take it into the Apple store. I don't want to get overcharged for parts, get charged for labor, and wait for them to do it all when I have the internet (and forums such as these, included) to help me figure out the problem, learn how to replace/fix the problem, and not to mention, the parts are cheaper. I've held out on purchasing a new 1TB HD as a replacement, and a new HD cable until I can decide on what the problem is. When I get the USB enclosure I'm sure things will be clearer right? I'll put helpful information below here if I remember anything that's useful: A ran a full system diagnostic test (the extensive one) by holding down "D" at startup and the results came back with nothing helpful- it said everything was OK. This is with my old original HD in. Also with the old original HD in, I ran disk utility and when I verified the disk it came back OK. TL;DR- I can't figure out whether the issue I'm having lies with the HD cable or the HD itself and I'm going crazy trying to diagnose/fix the problem. Is there a way I can find out which one (even if it's both of them) is the culprit?