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Upgrade the internal Fusion Drive to an SSD and boot entirely from new drive?


macrumors member
Original poster
Feb 29, 2008
it's time to finally update my Late-2013 iMac CTO 27" (3.5GHz i7) w/3TB Fusion Drive. Note that my current internal drive is at about 85% capacity! I am particularly interested in a new iMac/iMac Pro with an internal SSD and definitely want to stay away from a Fusion Drive. I recently upgraded a 2011 iMac to an OWC SSD, and was very impressed with how much snappier the machine was. I am also interested in improved graphics, i.e. 5K, for my viewing pleasure. To sum up, I want a (much) snappier machine with better graphics. I'm not a power user in terms of processor-intensive stuff. A couple of options that I was considering:

1. Update my current iMac with one of the OWC SSD upgrade kits. Note that I have used their kits in the past on at least 4 or 5 occasions, and have had very good success. The issue with this route is that, if I do install an SSD in place of the HD portion of the Fusion Drive, Could I install the OS entirely on the new SSD, and then boot only from the SSD? I know that most suggest that you install the OS on the built-in blade SSD, and then install apps and data on the SSD, but is it possible to install everything on the new SSD and have it the sole bootable drive?

2. Purchase a 2017 or later iMac and boot from an external T3 NVMe drive. This will probably be a future-proof option.

3. Purchase a used iMac Pro and boot from an external T3 NVMe drive. Overkill, probably. but they look cool.


macrumors 68000
Oct 19, 2007
Nambucca Heads Australia
Depends what youy mean by 'future proofing'

OS X.11 Big Sur from all reports will only run on later iMacs, 2014+, by September next byear even they will be dropped from futers operating systems. For mine I would go Option 2 preferably with a large enough SSD.
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