My iMac HDD just gave up after making a loud clicking noise for several weeks. Since the internal HDD is dead, I want to use another disk, preferably an SSD. I do not want to go to a store at any point and so I looked into taking the iMac apart and replacing the HDD myself. Seems like a hassle that I would like to avoid if I can simply plug in an SDD into one of these three:

  • USB 3.0 port
  • Firewire port
  • Thunderbolt port

My question is that assuming I do NOT want to exceed $150, which one of these gives me the best speed such that I would not miss having an internal drive? Can a drive connected to one of these ports be enough to not need an internal drive at least speed-wise?

  • you can get pretty much any external HDD, then install from the internet recovery partition by pressing I on boot. You may find more info on internet recovery at Apple's Help Page
    – bret7600
    Feb 5, 2018 at 19:28

2 Answers 2


There is no hard and fast rule for this. Sometimes when a HDD fails to boot, you can boot from another attached bootable disk. Sometimes, however, the HDD fails in a way it won't permit booting from attached drives because it seems to monopolize the bus.

You don't have USB 3.0 or firewire on this, even if it is a late 2011 iMac core i7. So you'd be limited to Thunderbolt or USB 2.0, which is going to be a little slow.

I know iMacs are hard to take apart, but your best bet is to look at the instructions or video on how to install an internal SSD from Other World Computing (MacSales.com) or, iFixit.com. If you think this is possible, it's a cost effective way to really fix your iMac and make it a lot faster.

edit: I wanted to add that USB 2.0 external HDDs are cheap and slow, Thunderbolt drives are expensive, and you can now get a decent SSD to install internally within your budget.

  • Thank you. One last thing: since this is an old iMac and I will purchase a new SSD drive, is there an adapter case that I would need because disk drivers are different in dimension these days than in 2011?
    – learnerX
    Feb 6, 2018 at 6:11
  • I think there is no change is size.
    – Pratik
    Feb 6, 2018 at 8:06

Artiste212 is right. I believe the internal SATA bus connection is not compatible with older legacy USB format drives without a Swiss Army Knife with a SATA connector/converter.

Definitely not ideal for every day use.

I did as Artiste for my 2011 MacBook Pro. Replaced my system drive with an SSD first, then replaced the optical drive w/an internal storage 1 TB SSD. Just follow Other World Computing’s you tube videos. Extremely easy, but wow what a performance booster!!!

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