The joy and pain of upgrading a 27-inch iMac with a SSD
The next thing I knew, my piggy bank took a hit thanks to a 240GB OCZ Vertex 2, which promptly arrived yesterday. Sure, it may not be the sexiest 3.5-inch SSD in the world, but it's what's inside that sealed the deal for me: a SandForce SF-1200 controller that delivers up to 285MB/s and 275MB/s read and write speeds, respectively, and up to 50,000 IOPS for 4KB random write. As for the tools required for this upgrade, the always helpful iFixit lists a pair of suction cups (for removing the glass), T8 and T10 Torx screwdrivers, and a pair of tweezers. Oh, and the iMac's restoration discs would be useful as well, of course.
Luckily, all I needed to get from the shops were the suction cups, so it didn't take long before I started backing up my files onto an external drive, and then getting my hands dirty with the iMac's innards. To my surprise, the only things that held the glass cover in its place were just a few strong magnets dotted around the border, which meant little effort was required to lift up the glass with the suction cups (but with caution in case they lose suction). The next step was to simply remove the eight Torx screws, although the nearby magnets did have a tendency to steal those bits or pull away our screwdriver. After that small hurdle, things got a lot trickier: the LCD assembly was way heavier than I expected, yet I had to single-handedly keep it lifted up slightly in order to disconnect the four short cables underneath, before I could carefully lay it down on my bed. If you're planning on performing the same upgrade, note that the tiny cable nearest to you does require some patience when both removing and re-inserting -- a pair of good tweezers will be super handy.
It was a breeze from then onwards: I just had to set the hard drive free and transfer its Torx pins, bracket and EMI foam to my brand spanking new SSD. Okay, fine, I did manage to install the bracket upside down in the first place, but that was the least of my concern; the bigger problem was that my SSD didn't have a socket for the iMac's two-pin thermal sensor plug. Initially I just left the cable dangling and put everything back together, but after installing OS X, the iMac got me worried with its fan running at full speed all the time. After some research, it turned out the only solution was to short the sensor cable -- I just cut a small piece of tie wire and inserted both ends into the cable's terminals, and voilà! The fan stopped spinning like crazy. But beware: since the logic board can no longer read the SSD's temperature, it's best to use programs such as smcFanControl to give the fan a little kick once in a while. If you're using a 2.5-inch SSD, turns out some 2.5-inch-to-3.5-inch adapters do come with a built-in thermal sensor; alternatively, you can just slap on a bog-standard optical drive thermal sensor (see "More Coverage" link).
So after some much needed dusting on the LCD and underneath the glass, we carefully placed the glass back in its place and booted up the now speedy machine. Having restored most of the essential files and applications, we still achieved an impressive boot time of around 20 seconds -- that's at least three times faster than before. As for general usage, even though our Xbench numbers aren't anywhere close to the advertised speeds, we've definitely noticed a huge improvement in our usual workflow, especially with resource hogging programs like iMovie and Photoshop. Whether this shining performance will sustain, only time will tell, but one thing's for sure: this early Christmas present for myself was totally worth it.