My Mac was slowing down, beachballing, and disk utility demanded erasure and reformatting twice. The day after the second restore from a Time Machine backup . . . my iMac turned on and gave me the universal NO symbol, and some kind of mech kernal error.
Thanks to the confidence instilled in me by the repair guide, the comments, the exact tools I bought from iFixit and Crucial's website SSD recommender, I really truly (and successfully!) opened up my iMac, removed the dead drive and installed the new one. If you told me a month ago that I would of done this, I would of quickly found a way to get away from you. I'm glad you didn't do that because then I would be feeling really guilty now.
The repair guide by Brittany is wonderful, yet as we all know nothing is perfect. She knows it too which explains why she probably fizzed on step 11 in order not to break the nothing perfect rule. It's true about what they say about step 11 in the comments. Just remove the cable from THE SCREEN and not the board. I could tell from the loose tape over the connector that that is exactly what the Apple Genius Pro Technician did when I brought my iMac in for warranty repair way back when.
Also here is a sad but true story for you. Knowing that SSDs run cool compared to an HDD, especially when they are in an IcyDock converter, I super-intelligently did not reconnect the hard drive thermal sensor to the new drive nor the logic board. I just left it a hangin' off the old drive as I chucked the whole thing into the can. Unfortunately, after finishing putting my iMac completely back together and turning it on, the fan ran at a speed I never thought possible. Evidently with the thermal sensor missing, the fan logic circuitry reads it as an overheated hard drive and runs at full throttle. So yes, I opened her up all over again and placed the thermal sensor so my fan can go back to sleep.
I inserted my Snow Leopard Install Disk, ran disk utility so I could name my new SSD -Macintosh HD- under the Erase tab. Thus, when I went to restore my computer using a Time Machine backup, the new drive, Macintosh HD, was seen by the software and offered it as a selection to become the startup disk. When I did not name the drive the first time, there was nothing to choose from.
Have fun and all the best!
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