I'm out of space on my Mac so I've been planning to buy an SSD and install some programs there. I know that USB 2.0 has a low bandwidth so there is no point to use SSD through USB 2.0. The question is how do I connect an external SSD drive to my MacBook Pro 2014 that doesn't have Thunderbolt 3 jacks, hence I can't connect USB 3 cord to it. There are some adapters from USB 3 to Thunderbolt 2 that apparently cost about $100-150 so I would avoid buying them if possible.

Thanks in advance!

  • Are you looking for a hardware recommendation or a how to guide? One of these is off-topic.
    – user1691
    Nov 22 '17 at 19:14
  • @SiXandSeven8ths I'm not sure, I'm not very familiar with this. I can connect everything myself so I don't think I need a how-to guide though I don't know which exactly hardware I need to accomplish this. Nov 22 '17 at 19:46
  • @SiXandSeven8ths, it sounds like a request for "hardware and how to use it", though for any hardware likely to be suggested here (rather than on, for example, Electronics SE), the "how to use it" is "plug it in".
    – Mark
    Nov 22 '17 at 20:33

TL;DR: Don't. Get an SD card.

Let's start by taking a tour of your MacBook's I/O:

enter image description here

For sake of simplicity and feasibility, we'll explore three options here: USB, Thunderbolt, and SD.


Contrary to your original question, you do have USB 3.0! We won't go into it much, but the newer port you're referring to is USB 3.1 Type C.

USB 3.0 has a maximum speed of 5 Gb/s–below SATA 3's 6 GB/s, but still above most (even fairly fast) SSDs. All good then, right?

Unfortunately, through a combination of packet problems, controller issues (either on the computer or enclosure end), and general magic, USB 3.0 just... isn't that fast. I'm not particularly well equipped to say why, and I wouldn't be surprised if more in-depth analysis revealed flawed testing methodology, but that's the fact of the matter... for now. Still, 3.360 Gb/s isn't anything to scoff at, nor is it too far from advertised.

Thunderbolt 2

Thunderbolt is kinda the big daddy of external expansion. It advertises 20 Gb/s over a 4x PCI-e 2.0 connection. And for the most part, it delivers... 11 Gb/s. Akito specifically cites the chipset (rather than the protocol) as the limiting factor. Still, that's enough to handle the fastest SATA SSDs, and even decent PCI-e drives.


The SD spec promises speed up to 2500 Mb/s for UHS-II. You won't get that on a MacBook Pro, since the reader is connected over a USB bus–in your case, USB 3.

One thing to note is that the maximum file size you can put on an SD card varies. Normal SD cards support 2GB (avoid!), SDHC cards support 32GB, and SDXC cards support 2TB.

Choosing your connection

With this in mind, we get the following:

  • USB enclosure: Lower speed, greater flexibility with drive choice, medium price
  • Thunderbolt enclosure: Better speed, greater flexibility with drive choice, PCI-e support, high price
  • SD: Lower speed, lower flexibility with drive choice, low cost, much better portability

Note that USB and Thunderbolt are fundamentally incompatible specifications; you cannot convert Thunderbolt to USB.

Given that you're using this for secondary storage on a computer with an already very fast SSD and (based on the fact that you said $100-150 was too expensive) price is important, SD cards seem like the way to go. You can even get ones that lie flush with the rest of your laptop, or microSD adapters that allow you to bring your own SD card.

enter image description here

Since you haven't provided a specific price or storage requirement, I can't get more specific than that.

If you have no regard for money or physical space considerations, the Sony 128GB SF-G Series UHS-II is among the best I know of, and comes with a 5 year warranty and data recovery to boot, though I would advise against this. I would recommend something along the lines of the SanDisk 128GB Extreme UHS-I and one of those microSD flush-fitting adapters from earlier.

The exception to this is if you want a large amount of storage (256GB+ mostly.) SD cards at this price point are still much more expensive than their desktop counterparts while offering worse performance, though this breaking point will likely change in the future as SSD prices continue to drop.

  • 1
    In my experience, SD cards are a very poor choice for general-purpose storage. The controller is usually optimized for the FAT32 filesystem and a write-mostly workload consisting of small numbers of large files. For a read-mostly workload and large numbers of small files, a card could well be slower than a spinning hard drive.
    – Mark
    Dec 26 '17 at 21:10
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    @Mark That depends extremely heavily on which SD card you get. Think of the SD cards that go into professional video/photo cameras: they support large, sustained read/write workloads for extremely large files (which wouldn't be supported by FAT32...) or many small files at extremely fast speeds. That's why I wrote "Since you haven't provided a specific price or storage requirement, I can't get more specific than that." There's a reason SD cards range from $50 to $250 for the same capacity.
    – JMY1000
    Dec 26 '17 at 21:16
  • @JMY1000 Wow thank you very much for detailed explanations! I haven't even considered this option before, I didn't know these SD cards could be so fast. Which one would you recommend buying without taking the price into consideration? Dec 29 '17 at 17:08
  • @IvanYurchenko I've edited my answer, take a look and let me know if that answers your questions!
    – JMY1000
    Jan 1 '18 at 2:17
  • @JMY1000 Thank you! Jan 3 '18 at 12:07

I would recommend buying an express card with the esata port. This will allow for much higher data transfer speed over your FireWire or usb options. Newer esata runs at speeds of around 6gb/s so you will probably get the speeds you need with that. You can find express cards with the esata option for around $20-$30. If your looking for speeds in excess of 6gb you will need to upgrade to use usb 3.1.

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