The spot chosen for the location of the additional solid-state drive in the new 27in iMacs will be of great interest to anyone thinking of upgrading. Previously, the SSD option was available only on 27in models and, frankly, only viable as an original-equipment purchase. Computers sold with just the standard mechanical drive lacked fixing brackets for an additional drive and fitting one was an expert job that involved lots of improvisation. Frankly, it wasn’t to be recommended.
SSDs can now be specified on the 21.5in 2.7GHz model and ifixit’s teardown of this version indicates that the drive will be located beneath the optical drive. So far we haven’t seen the internals of the 27in model but it will be interesting to see if there is clear provision, with fixing brackets and connectors, for the SSD. I can see every reason why Apple would want to make it simple to add an SSD and, equally, little incentive in making things difficult just for the heck of it.
The area shaded in red in the….picture is presumably where the optional SSD is housed. The three mounting points within the shaded area have nothing attached to them in our machine, since this option is only available on 2.7 GHz 21.5” iMacs. (description and photo, ifixit)
Another observation: Since the big advantage of an SSD is speed for reduced start-up and application access times, there’s a good case for fitting a 128GB device instead of the 256GB, which is the only option currently offered. My MacBook Air 11in manages quite well on 128GB and, at a pinch, could scrape through on only 64GB as did the original Airs. So 128GB would be perfectly adequate for system and application files on the iMac, leaving the main mechanical storage for data.