Experiencing strange performance issues after a hard drive failure - Help!

Question

I bought my mid-2012 i5 Macbook Pro in December of 2012. I realized when shopping for computers that I wanted an SSD installed, but that it would be a lot cheaper if I bought the SSD and installed it rather than customizing it in the Apple Store. So I bought a nice Samsung 128GB SSD (820 or 840 - can't remember which) and did the installation. I went ahead and installed two 4GB sticks of RAM while I was at it. Everything was just dandy: my boot time was just under 9 seconds, and all of my data-heavy apps booted in no-time at all. Then all **** broke loose.
About two weeks ago, I opened my computer and I got the dreaded "? File Folder" notification with a gray screen. I immediately thought hard drive failure. No matter how many times I tried to boot, the computer just would not talk to the SSD anymore. I used Internet Recovery to get into my Disk Utility, and the entire partition was gone. I assumed the worst but wanted to be sure - I bought a hard drive enclosure and hooked the SSD up to an older Macbook, and lo and behold: it worked perfectly. I was not only able to recover data, but I could write data to the drive. Nothing appeared wrong with the drive when I plugged it into the old Macbook, but my newer Macbook still would not recognize it. Even my fiance's Windows 7 PC recognized the drive as "?" (since it was formatted for Mac, but hey - it recognized that it existed!).
I decided to re-install the original HDD that came with the 2012 Macbook Pro (the one I removed in favor of the SSD). I was able to re-install the OS and I can boot up at will, but everything is different. The performance issues are extremely noticeable. I can't have more than two programs running at one time without the spinning wheel of death appearing. My boot time went from 9 seconds to 2 minutes. I know that SSDs increase performance, so there is some slight performance downgrade to be expected since I am using a mechanical drive now -- but these are not normal issues. Sometimes I can't even type a web address into Safari without the wheel appearing. iTunes, and specifically the App Store, take minutes to open - and I have no media is on iTunes.
Here's the thing: I have tried just about anything to fix this problem that Google can pull up. I've verified the HDD, I've booted into Safe Mode, reset RAM and cache, run benchmarks and other performance tests, entered all sorts of weird language into Command Prompt, and studied Activity Monitor - I can't find a single red flag that would indicate anything being wrong. It appears to be a perfectly functioning, updated computer.
I'm thinking a piece of hardware failed that triggered the error with the SSD. I'm not really sure though since all of my performance tests indicate perfectly functioning hardware. I'm a little afraid to take it to the Apple store because I know they'll tell me it's my fault for opening the computer and replacing the hard drive in the first place.
Any ideas? At this point anything to salvage this computer would be helpful.

Answer 1

Spin Cycle,
were those other computers which were able to recognize your SSD in its external enclosure also Macs? Do you know if your SSD has its most recent firmware revision installed? (If it doesn’t, its installer can be downloaded from the Samsung SSD firmware page for burning onto a bootable DVD.) I haven’t used the 830 myself, so I don’t know what its reputation is with Macs. I have an 840 PRO in my MacBook Pro, which has been trouble-free for me, but my understanding is that the 840 EVO has had trouble with Macs in its earlier firmware revisions — so I’m wondering if the 830 has a known track record with Macs, good or bad.