MacBook Pro 2009 new hard drive install results in very slow function and freezing

Question

I just wanted to post my resolution to a problem that I had trouble finding an answer to on these forums.
Short version:
I replaced the hard drive in my 2009 MacBook Pro because the computer froze and upon reboot the Disk Utility said it was corrupted, but with the new hard drive the computer ran very slowly and often showed the spinning rainbow wheel. I replaced the SATA cable that connects the hard drive to the motherboard and it works perfectly once again.
Long version:
Recently my MacBook Pro (2009 running Snow Leopard) froze up and I performed a hard reset by holding down the power button. When I turned the computer back on it would not boot OS so I ran disk utility from the Snow Leopard install DVD. The test said the hard drive was corrupted, and since the computer is way past warranty I decided to change the drive out myself. I bought a 500GB Seagate Momentus 5400 Drive from Amazon, opened the computer and replaced the existing hard drive with the new one. When I first booted from the OS install DVD, my computer was not recognizing that any hard drive was present. I read somewhere on these forums that sometimes the formatting on new Seagate drives can't be read by MacBooks and they need to be reformatted using another computer, but I tried simply taking the hard drive out and putting it back in a couple of times thinking maybe I had just not plugged it in correctly. After the 4th attempt the hard drive magically showed up, and I was able to reformat the drive and install OS and even Windows XP on bootcamp.
Everything seemed to be okay but applications were running slowly considering this was a fresh drive and OS install. Over time, the computer started to hang more and more. In OS I would get the spinning rainbow wheel even when doing something as simple as opening a browser window in Chrome or trying to type into a text field. When I tried to use Windows it would simply freeze after only a short time and I'd have to do a hard reset.
I went to the Genius Bar at the Apple store which was unhelpful, so I continued searching through these forums to try to figure out the problem. I noticed a lot of people had trouble with the SATA cable that came with the computer because it's quite thin and delicate, and would get damaged when changing out the hard drive. However most of these people seemed to experience a question mark when starting up the computer, whereas mine would fully boot and be functional for a time. I thought it unlikely that a damaged cable could possibly leave the computer partially functional. Finally though I gave in a dropped the $26 for a new SATA cable on Amazon. As soon as I installed it the problem was fixed, and the computer runs as fast as when I first bought it. I don't know if I damaged the cable changing the hard drive (I was extremely careful) or if my original hard drive was not actually corrupted and the cable was already damaged. I mentioned the possibility of the cable being damaged at the Apple store and the representative said that often times they fail because people carry the laptop with one hand, and because of the way this model was designed this puts a lot of pressure right on that thin cable. Regardless, if you do plan on changing out your hard drive in your MacBook keep in mind that the SATA cable is sensitive, and that if you experience problems with a fresh hard drive and OS install the SATA cable is a likely culprit.

Answer 1

If you think you have either a hard drive or a cable problem, to the best of my knowledge the only product that can help isolate both of them is Scannerz. You can check it out at:
http://scsc-online.com/Scannerz.html
I think that's the correct link. If it isn't and you're interested and that's wrong, just google it. I'd also check out their downloads section, especially the sort of short document on using path isolation to detect and isolate problems.
Scannerz can detect both errors and irregularities. It uses the surface scan progress as a reference. Cable problems never show up at the same location because they're typically intermittent. Surface problems always show up at the exact same place. That's the only product (at least commercially available) that can do that.
I don't know if this information is of any value to you because it sort of sounds like you've already solved the problem, but it might be of use if you have problems in the future.
In any case, I've seen several posts on several different sites where people were reporting insulation break down on some of the SATA cables. Apparently the insulation breaks down and the cable starts shorting to the case.