I have a 2011 iMac 27", and back then opted for a HDD. Back then (and now still) I fear for the lifespan of SSDs, and hauling an iMac 27" to the store is cumbersome, so it looked the right choice.

But now, I notice that the drive is the main bottleneck for pretty much anything I try to do, and I would love to benefit from the better performance of an SSD. (Though still not regretting my choice for HDD internal storage, mind.)

Will installing OS X and my applications on an external SSD be faster than an internal HDD?

If I did my reading right, I really should be getting something with a Thunderbolt connection. But I wanted to check here to be sure, and wondered if OS X is at all bootable from a Thunderbolt drive?

  • I guess if you chose the SSD as your initial mounting drive then I guess. I would do this and then have all my files on the internet HD
    – Phorce
    Jan 25, 2013 at 18:14

2 Answers 2


To answer your first question, Yes booting from an external SSD should be much faster than a stock HD.

Thunderbolt is definitely the fastest interface around so that shouldn't be the bottle neck.

Yes, from a brief Google search it looks like people are booting from Thunderbolt drives without a problem.


I own a Lacie Rugged SSD USB3/Thunderbolt 128 GB drive.

I am using it as a boot drive for my 2011 iMac over Thunderbolt.

I had no issues with it, I put the iMac into sleep over night. The drive never disconnected when a I woke up the machine from sleep. Although the drive is not as fast as an internal drive but it is a good option for an iMac if you do not want to install an internal SSD into an iMac.

This option is a lot faster than the internal 7200 rpm HDD. The apps load very fast. Before that I had a lot of problems with a lot of apps opened especially when I ran out of RAM. But I have no problems now using the SSD.

Some reported that you can not enable TRIM on an external SSD. I enabled TRIM with TRIM Enabler.

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