I have a mid-2010 27" iMac. I want to speed it up some and I have decided to get an external SSD. I want to make this my boot disk as well as data storage. The SSD I'm considering is 3 TB. My concern is the connection speed. The 2010 iMac has USB 2 I believe and a Firewire 400. The drive I'm considering has USB 3.0/3.1 and a Firewire 400 connections. Will these be sufficient to use with my iMac? Which connection would be better-suited speed-wise. The Firewire 400 or USB 2?

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    You'll get better performance using an internal SSD on the SATA bus, otherwise if you are going to use an external SSD on that system, I'd go with FireWire 800, as that's what your iMac has, over USB 2. – user3439894 Aug 16 '20 at 4:58
  • @user3439894 You can't accidentally eject the boot volume. Can you explain why using screen will help? – benwiggy Aug 16 '20 at 10:44
  • @benwiggy The shell running inside screen will have its current directory on the external disk, so there is an open file which prevents ejection. – nohillside Aug 16 '20 at 11:17
  • But as said, you can't eject the boot volume (short of yanking the cable). – benwiggy Aug 16 '20 at 14:06
  • @user3439894 - Thanks very much for your comments. Where did you get your info on my iMac model? I thought I had firewire 400. I can't replace the internal drives so I'm going the external path. – Natsfan Aug 16 '20 at 14:12

FireWire 800 is the fastest external connection you have, and roughly matches the 6 Gbps speed of the SATA III drive interface, (though 'real-world' performance may be reduced, and a direct internal connection may be slightly faster).

FW 400 is, as the name suggests, half the speed.

USB 2.0 is considerably slower.

Using anything other than FW800 is going to limit the benefit of having the SSD.

I'm surprised that any manufacturer is producing a drive with USB 3.1 and FW 400, rather than 800, TBH.

  • The external drive I referenced had Firewire 400/800. – Natsfan Aug 16 '20 at 13:59
  • @jmh Then get that one. It's the best option for your iMac. – benwiggy Aug 16 '20 at 15:34
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    RE: "FireWire 800 is the fastest external connection you have, and roughly matches the 6 Gbps speed of the SATA III drive interface" -- "roughly" ... Not even close! – user3439894 Aug 16 '20 at 15:40

This doesn't directly answer your question, but may be some help.

I have an early 2008 iMac, the entry level 24" iMac 2.8GHz processor, 2 GB RAM, SuperDrive, ATI Radeon HD 2600 PRO with 256MB of VRAM and a 320 GB HD.

Many years ago I upgraded to 6GB RAM and installed a 2TB Seagate SSHD Solid State Hybrid Drive (a physical HDD with an SSD flash module) which mimics Apple's “Fusion“ drive. These upgrades still work perfectly.

The performance improvements were remarkable... prior to the upgrade MS Excel was taking over two minutes to load and following the upgrade, it took literally a few seconds. Boot time dropped from about two and a half minutes to less than one minute.

In fact the machine still works perfectly despite no longer been supported by OS upgrades.

The reason I'm suggesting this:

  • as per comments by @user3439894 the performance will be much better;
  • it is not difficult to do the work to swap the drives yourself.

If you're interested in pursuing this option, there is an excellent guide on iFixit that provides detailed step-by-step instructions.

Also as mentioned by @user3439894 and as quoted from Apple's support website, your machine has:

One FireWire 800 port; 7 watts

Your iMac also shipped with 4GB RAM. I'd strongly recommend you consider upgrading this to 8GB RAM. There are a few good websites that help you pick the correct RAM for your iMac and replacement modules should be reasonably priced. This is an easy upgrade as the RAM modules can be switched out without dismantling any part of the machine. Only need to remove the RAM slot cover = 1 screw. Refer to the Apple Support website for instructions.


As mentioned by others, I grabbed the technical information from Apple’s website “iMac (27-inch, Mid 2010) - Technical Specifications”

This image from Apple’s website Identify the ports on your Mac, should help you identify which FireWire you have:

FireWire diagram

If your ports are inaccessible at the current time, instead use this technique:

  1. Click on the Apple logo top left of your menu bar;
  2. Open “About This Mac”;
  3. On the Overview tab, click on “System Report...”;
  4. Scroll down the list under the heading “Hardware” until you find “FireWire”.

Clicking on the FireWire subheading should confirm your FireWire type.

As mentioned by David Anderson in the comments, you have a few options to upgrade storage internally. Not sure if that requires a new question, but happy to provide my decision making process, if you’re interested. Essentially you can:

  1. Swap out the SuperDrive for an SSD leaving the exisiting HDD in place;
  2. Swap out the HDD for an SSHD or SSD and leave the SuperDrive in place.

I chose the latter because it was the easiest upgrade and in my humble opinion the most cost effective, also I was nostalgic about keeping my SuperDrive (nothing to do with a logical decision!).

  • Thanks very much for your input. It's good to hear your upgrades performed so well. Where did you get the tech info about my iMac model? I have a different source and it has conflicting information. I'd like to check my specs against what it says. Thanks again for your input. – Natsfan Aug 16 '20 at 14:06
  • Very thorough and useful answer. – Seamus Aug 16 '20 at 15:30
  • Here are the links to the iMac (27-inch, Mid 2010) - Technical Specifications and Apple Technician Guide iMac (27-inch, Mid 2010) PDF file. OWC is a good source for SSD. OWC also has good installation videos. Look like you could add an internal SDD and keep any existing HDD. – David Anderson Aug 16 '20 at 18:20
  • @jmh I’ve updated my answer with some extra info. – andrewbuilder Aug 17 '20 at 1:03
  • @andrewbuilder Thanks for the info. I checked the FireWire connection speed and it was listed as 800. That's a real relief to confirm that, as I ordered a 1 TB external SSD with firewire 800. I can't upgrade the internal drive even though the current drive is failing! – Natsfan Aug 17 '20 at 1:15

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