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Thunderbolt Unleashed – A Comparative Review of PCIe Expansion Devices for Macs

Thunderbolt Unleashed – A Comparative Review of PCIe Expansion Devices for Macs

Mac users everywhere were buzzing with excitement when Apple unveiled the new Thunderbolt port on their MacBook lineup in February of 2011. The standard was developed jointly by Apple and Intel, and served at the time as the fastest and most advanced I/O method ever offered on a consumer computer – far faster and more powerful than FireWire or USB.

Thunderbolt MacBook Pro

I remember how excited I was as I eagerly followed live blogs of the Apple event. Thunderbolt had so much promise – and Apple had already been working with a bunch of manufacturers to make sure there would be devices to support the new standard. It’s now July of 2013, nearly two and a half years later, and now that the initial buzz has died down, I can’t help but wonder…what happened to Thunderbolt?

28 months later, there’s still only a relatively selection of Thunderbolt-enabled products to choose from, and the majority of those are both expensive and designed for professionals rather than consumers. Even among “pro-sumer” and professional Mac users, only a fraction actually make use of the Thunderbolt ports on their Mac – and I can’t help but think that part of the reason is that they don’t really see or understand a benefit to doing so.



Neither consumers nor pro users need to feel left out entirely of the Thunderbolt boat. There are somewhat cheaper ways to use Thunderbolt to expand the utility of your Mac today than there were when Thunderbolt was first released. One great way to make use of Thunderbolt is by using a PCI Express expansion chassis, allowing you to hook up PCIe cards to your Mac, adding additional ports, powerful video processing cards, additional hard drives or SSDs, and more.

We decided to get our hands dirty and evaluate three such devices from competing brands to find out which one offers the best blend of affordability, power, and performance in an attempt to show you which devices are available for expanding your Mac through Thunderbolt, and helping you sort out which of the offering might be right for you, your Mac, and your budget.

Benchmarking and Test Methodology


While we lacked the necessary hardware to test the actual power output performance of each expansion unit (OS X does not currently support using things like high-end graphics cards over Thunderbolt), we were able to do some fairly thorough testing of their data transfer performance, which makes up the basis of our benchmarks. The units were tested using a 2013 MacBook Air and late 2012 27-inch iMac (interchangeably) with clean installs of OS X Mountain Lion, a set of 4 500GB Samsung 840 SSDs, which were set up in a striped RAID array to maximize their data transfer speeds, and two Sonnet Tempo SSD PCIe cards to hook them together. I also used a pair of 512GB OCZ Vector SSDs interchangeably to see if it made a practical difference in the end result (and it actually didn’t, since the SSDs were operating faster than Thunderbolt could keep up with anyway). The benchmark results were captured using both BlackMagic Disk Speed Test (free, Mac App Store direct link), and the DigLloydTools suite of benchmarking utilities.


Aside from raw data performance, we also evaluated the design and value of each device in order to get a complete picture of exactly how each compares in both raw power and the experience of actually using the devices on a day-to-day basis.

The Hardware

Magma ExpressBox 3T



Magma was among the first manufacturers to release a Thunderbolt to PCI Express expansion box (with their original ExpressBox 3T design released in September of 2011), and the knowledge they’ve gained from experience is certainly evident in their product. The Magma ExpressBox 3T is a sturdy, beautifully engineered device, crafted from the same anodized aluminum that Apple uses to build Macs. As a result, the ExpressBox 3T looks fantastic on a desk next to Apple products – almost as if it were designed by Apple themselves.

Of the three expansion boxes we tested, the ExpressBox 3T not only provided arguably the most solid and sturdy build – it also provided the easiest access for inserting and removing PCIe cards. Simple removing the finger-bolt in the back allows you to lift the top panel off of the unit, giving you full access to its trio of PCIe slots.


While the ExpressBox 3T is quite elegant, sturdy, and easy to use and work with, however, one thing that it definitely isn’t great at is noise control. While the box’s internal fan isn’t exactly loud, it is significantly louder in operation that the Sonnet Echo Express Pro we tested, and was very noticeable at all times the device powered on – especially in a quiet office environment. I’d have preferred Magma to choose a quieter, more efficient fan, or devise some method of muffling the constant whirring/buzzing the unit generates. The fans were especially noticeable when the unit was put under a great deal of stress – like a data transfer using 4 RAID-chained SSDs for upwards of 1-2 hours at a time.

Finally, one thing particularly worth noting about the ExpressBox 3T is its guts – the PCIe slots inside are placed extremely well – they’re far enough apart to make inserting and removing a single-width card extremely easy, but close enough together that the device keeps as narrow a footprint as possible on your desk.


We’ve already established that Magma’s Thunderbolt expansion units are extremely well-designed – but the more important question is: how does it perform? The answer? Very, very well. In fact, of the three units we tested, the ExpressBox 3T consistently gave us the fastest data transfer speeds with an identical SSD RAID setup than either the Sonnet or One Stop Systems products.

SSD RAID Thunderbolt 3

We were able to consistently achieve data transfer rates upwards of 880MB/s read speeds and 875MB/s write speeds. The above Disk Speed Test screenshot represents the average of 4 separate benchmark tests performed with the device. Unfortunately, it’s louder fan speeds made it difficult for me to choose raw power above all other factors.

For what it’s worth, the louder fans are not without purpose, however – they enabled the ExpressBox 3T to run slightly cooler overall than either of the other brand offerings, which can be important for long-term drive health.

Summing it Up


  • Solid, sturdy construction.
  • Offers the best raw benchmark performance of any of the devices we tested.
  • Extremely easy to add or remove PCIe cards.


  • Fans are quite loud, and can distract from a quiet office environment.

 Note: I also received an ExpressBox1T on loan from the manufacturer – but since I couldn’t test it in exactly the same capacity, using 4 SSDs (it only has a single PCIe slot), and its design was extremely similar to the ExpressBox3T, I opted not to include it in my testing.

Sonnet Echo Express Pro


Sonnet was on the scene with their first Thunderbolt PCIe expansion chassis in early 2012, and have been offering such devices nearly as long as Magma has been. Their Echo Express line of Thunderbolt expansion units share a number of similarities to Magma’s units in terms of quality – like Magma, Sonnet also builds their units out of a healthy amount of Aluminum, and also styles their products similarly to Apple’s products. Aesthetically, and in terms of quality, it’s difficult to drive a wedge between the two company’s devices – at least in terms of declaring one “better” than another.


One way Sonnet’s products stand out in the crowd is in terms of aesthetic style. Sonnet’s products are somewhat more “stylized” and less “industrial” than other competing products, which gives their units their own very unique look. Adding and removing cards with the Sonnet chassis is also extremely simple – although rather than allowing top-down access like Magma’s products, Sonnet’s products require you to slide the outer casing backwards in order to install or remove PCIe cards. In some respects, this makes it more difficult to quickly add or remove a card – but only by a small margin.

Another thing I came to greatly appreciate about the Echo Express Pro is the fact that it’s  practically silent – MUCH quieter in operation than either of the competing brand products we tested. This came a quite a delight, especially in my relatively quiet, subdued home office. Finally, Sonnet’s products are slightly heavier and more solid – but neither unit lacks in any sense in the durability department.



When it comes  to performance, I’m thrilled to report that the Echo Express Pro is certainly no slouch. All in all, it offered comparable file transfer performance compared to the Magma unit, and had the 2nd best benchmark performance overall. In real-world usage, the difference were negligible or nonexistent.

The Echo Express Pro was able to consistently achieve data transfer rates upwards of 870MB/s read speeds and slightly faster read speeds than the Magma ExpressBox 3T, consistently upward of 881MB/s. As with the Magma unit, the above Disk Speed Test screenshot represents the average of 4 separate benchmark tests performed with the Echo Express Pro. With very competitive data speeds, and quieter overall operation, the Echo Express Pro remains a serious contender.

SSD RAID Thunderbolt 2

Summing it Up


  • Solid, sturdy construction.
  • Very competitive overall performance.
  • Much quieter operation than competing devices.
  • Slimmer overall footprint.


  • Slightly more difficult to add and remove PCIe cards, especially if in a hurry.
  • Doesn’t offer quite as much space between PCIe slots, which can make it more challenging to add and remove cards.

One Stop Systems CUBE3

  • Design

One Stop Systems is a relative newcomer to the world of Thunderbolt – their product line was officially launched in January of this year, and has become widely available to purchase only within the last couple of month. In terms of design, I have to say that the CUBE3 that I tested fell short of expectations. Rather than option for a sturdy aluminum casing, the One Stop System products use a plastic casing with a metal frame inside. The plastic is also high-gloss, meaning it scratches easily, and the entire assembly comes of feeling somewhat “cheap,” especially in comparison to Magma and Sonnet’s offerings.


Further, the CUBE3 was the most difficult unit to add and remove cards from – the thumbscrews (of which there are three on the 8-PCIe-slot version that I tested) didn’t remove or re-insert very easily – and if the unit wasn’t lying completely flat, they sometimes wouldn’t go back in at all. Further, the design of the unit requires that you slide the entire frame assembly out of its plastic casing in order to access its PCIe slots at all. It also doesn’t match a “Mac” aesthetic very well at all – although in fairness, the product also isn’t specifically targeted to Apple users.

However, despite its design concerns, the CUBE3 – and its various-sized counterparts – have two key advantages. First, they offer significantly more power per card than any of the other expansion boxes, allowing you to use more powerful PCIe cards. Second, they offer units with up to 8 PCIe slots, while the most you can get with any other brand I have seen is at most 3 slots. As such, it could be the idea choice for those requiring a mass amount of expansion cards.


While I found myself wishing that more care had been put into the design and overall build of the Cube3, however, I also appreciated its slightly lower cost per card, and larger amount of available power per card than any of its competition. Further, considering that One Stop Systems has less experience in the industry than its competition, it seems fair to cut them a tiny bit of slack.

  • Performance

While the Cube3 did lack somewhat in the design department, it offered very serious performance when it came time to do benchmarks. While the write speeds of the CUBE3 were slightly lower than the Sonnet and Magma devices, the real world differences, as determined by using it to boot Mac OS X and perform common tasks, were quite minimal.

SSD RAID Thunderbolt 1

The CUBE3 consistently achieved write speeds of around 845MB/s or so, although its read speeds (which is what the majority of users will notice in practical applications) were right on par with the competition, hovering around 875MB/s. Despite its lower build quality, the fact of the matter is that the CUBE3 (and the rest of the CUBE line of products) offers a serious punch in terms of power – and the fact that you can get units with up to 8 full-length PCIe slots means it offers something that none of the competition even comes close to.

Summing it Up


  • More powerful – supplies more power per card.
  • Offers a greater number of slots than competing devices.
  • Acceptable performance, nearly on par with competing devices.


  • Significantly cheaper “plastic” build.
  • Overall lower quality and less sturdy than the competition


Now that we’ve compared the design and performance of one of the flagship units from each of the brands (One Stop Systems, Magma, and Sonnet), it’s time to talk about value per dollar.

Screen Shot 2013-07-17 at 5.59.19 PM

As you can see from the above chart, each brand’s products offer key advantages: One Stop Systems offers a lower overall cost per PCIe card, and generally offers more power per card. Meanwhile, Sonnet offers an extremely competitive price on a 2-card expansion unit with their $599 Echo Express II, and Magma offers a fantastic combination between price and power with their sturdy 3-card ExpressBox 3T for $979.

It’s also worth noting that, while One Stop Systems includes a Thunderbolt cable in the package for their asking price, you’ll need to provide your own cable if you choose either Magma or Sonnet’s products.

The full product list (with prices and links) for each brand is as follows:



One Stop Systems


In the end, the performance between all three brands of Thunderbolt PCIe expansion boxes was very comparable. Each of the devices was able to push very close to the practical real-world limitations of the Thunderbolt interface it is bound to. Further, while the Magma and Sonnet products certainly take the win in terms of design and overall quality, the One Stop Systems device makes up for its shortcomings with additional expansion capability and raw power.

None of these devices are bad choices – they each offer key benefits over their competition, whether that benefit comes in the form of price, power, or aesthetics and design. Which brand you choose is ultimately up to you – and if nothing else, you can be assured that, at least in terms of raw performance, your choice won’t limit your performance.

Whether you’re looking to boost the capabilities of your iMac, MacBook Pro, or MacBook Air, are looking for a companion device to make use of all those Thunderbolt ports on Apple’s new Mac Pro, or just want to make use of some extra ports, or storage space, there’s certainly a product between the three companies that should meet your needs.

For more information, make sure to check the Sonnet, Magma, and One Stop Systems websites for all of the details – or to get in touch with someone to discuss your particular Thunderbolt needs!

Note: No currently available PCIe Thunderbolt expansion solution allows the use of external video cards while connected to a Mac. OS X lacks support for Thunderbolt-connected video cards, and there are currently no drivers available to allow the use of external Thunderbolt video cards on anything other than Windows-based devices.