[EN] Review – Sonnet eGFX Breakaway Box 550

Review of the more powerful version of Thunderbolt 3 eGPU dock Sonnet eGFX Breakaway Box 550.


A few months ago we brought you our review of an interesting Thunderbolt 3 eGPU dock, the Sonnet eGFX Breakaway Box 350. It offers great specs and value, and is among the least expensive Thunderbolt 3 docks on the market. As its name suggests, it is a lower version of the Sonnet eGFX Breakaway Box 550 dock that we are testing today. We will have a look at their differences below.

The packaging of the eGFX Breakaway Box 550 is identical to that of the less expensive model. Inside of the package we find the dock, 0.5-meter long Thunderbolt 3 cable, power cable and instructions.

After the unboxing we will have a look at the differences between both versions. The visual differences are minimal. Aside from different branding on the front, everything else is identical. The higher version has screws with rubber rings, while the less expensive one doesn’t. I haven’t found any other differences in the docks’ appearance.

eGFX 350 left – eGFX 550 right

What sets the docks appart? The eGFX Breakaway Box 350 had one big limitation – the PSU. It is only able to power graphics cards with one 8-pin connector and one 6-pin connector. This means any higher-end graphics card, especially the non-reference models with higher clock speeds and bigger heatsinks, could not be connected. The eGFX Breakaway Box 550’s more powerful PSU solves this problem.

While the less expensive version supports 300 W graphics cards and 15 W charging, the higher version improves these values to 375 W for the GPU and 87 W for charging.

eGFX 350 down – eGFX 550 up

The more powerful PSU can power graphics cards with two 8-pin connectors. This means better compatibility with more GPUs, especially the more powerful ones. Graphics cards that require more than two 8-pins aren’t common, although there are several GTX 1080 Ti models on the market that require three 8-pins. However, those are extreme versions that simply wouldn’t fit in the dock, either.

In addition to better graphics cards compatibility, the eGFX Breakaway Box 550 can also charge notebooks with up to 87 W. Thanks to this feature, you don’t have to connect your notebook to the charger when it’s connected to the dock. It won’t work on all notebooks obviously. When testing on Lenovo X1 Carbon 5th Gen it worked flawlessly. Since the lower version of dock offers only 15 W charging, the X1 Carbon wouldn’t charge at all. If you connect the dock to a workstation or gaming notebook, it’s almost certain that you will also have to connect your charger to prevent the computer  from discharging and to get the best performance out of it. Thunderbolt 3 can only deliver up to 100 W, but gaming notebooks’ chargers usually have higher output than that.

The difference between docks can be seen on the main boards. The newer version has more components.

eGFX 350 left – eGFX 550 right


Now that we have listed the differences between the docks, let’s look at the difference in performance. But first, let’s have a look at the products we used during the tests.

The docks were connected to:

Intel Skull Canyon NUC6i7KYK – i7 6770HQ, quad-core, 3,4 GHz, Intel Iris Pro 580, 32 GB RAM

Lenovo X1 Carbon 5th gen – i5 7200U, dual-core, 3,1 GHz, Intel HD 620, 8 GB RAM

The docks were tested as follows – eGFX Breakaway Box 350 was fitted with an MSI GTX 1060 Armor 3G as in the previous review. The higher version eGFX Breakaway Box 550 received a special treat – the Asus Strix GTX 1080 Ti OC. It’s one of the best models of the GTX 1080 Ti on the market, which will help us to compare the differences between mainstream and high-end graphics cards, and the effects on the performance in the docks.

Note: the installation of GTX 1080 Ti Strix required the disassembly of the PSU; it wouldn’t fit otherwise.


If we were to fit the GTX 1060 to the eGFX Breakaway Box 550, there would be no differences in performance. What will be interesting to monitor are the effects of the client’s CPU power on the GPU performance, and the bottleneck of TB3 as well. It can transfer data at 40 Gbps which is much more than USB 3.1 Gen 2 at 10 Gbps. On the other hand, it’s still less than the standard X16 PCIe 3.0 slot on a motherboard with 126 Gbps throughput. Let’s have a look at the test results.


We will start with the 3DMark Firestrike benchmark again, since it’s a very popular application for benchmarking computers.

The tests on the X1 Carbon already show great improvement with the GTX 1060, but the increase with GTX 1080 Ti isn’t that great. Here we can see evidence of a bottleneck, especially on the combined score.

The situation on the Skull Canyon NUC is different since the gap between GTX 1060 and 1080 Ti is double the performance. This means that the NUC can utilize more of the available performance than the X1 Carbon.


The GTA V benchmark is the second test. We kept the settings the same from the last review – Full HD, normal graphical settings, anti-aliasing turned off. The goal of this test is to show the difference between the integrated graphics and docks. We will also monitor the effects of client’s CPU performance on the TB3 throughput and bottlenecks.


The results of integrated graphics and dock with GTX 1060 are identical to the tests in the previous review. The performance increase is enormous, but we can clearly see the difference between 2 and 4 core processor. More information can be found in our eGFX Breakaway Box 350 review.The performance of the GTX 1080 Ti was interesting. We can see some improvement on the X1 Carbon, but it’s not that big. Obviously we are not fully utilizing the potential of the GPU. An even more dramatic bottleneck can be seen on the NUC; the GTX 1060 and GTX 1080 Ti have almost the same results. Since the GTX 1080 Ti has better minimal FPS, it’s placed on the top of the chart. This test revealed how the clients can slow down the graphics cards like the GTX 1080 Ti to the level of a GTX 1060.


Let’s try a different scenario. In the previous test we hit the limits of CPU and TB3 connection. By increasing graphical settings and turning on AA we can transfer the demands to the GPU, which results in a decrease of the bottleneck on the CPU and TB3 side.

In Full HD and very high setting, the difference in performance between the GTX 1060 and GTX 1080 Ti is almost doubled. Let’s have a look on one more test – 4k with high settings.

The scenario of this test is very similar to the Full HD with very high settings. This time the GTX 1080 Ti delivers more than twice the performance of the GTX 1060. Once again we have successfully reduced the bottleneck.


The tests showed us that if you want to use a high-end GPU, it’s important to set the games to high graphical settings and resolutions, which ties the performance to the GPU and not the CPU and TB3 throughput. Playing games on normal settings to achieve high FPS is greatly limited, and usage of an expensive graphics card is useless. This was nicely displayed in the first test where the difference between GTX 1060 and GTX 1080 Ti was minimal, but the price difference is 400 – 500 €.

The eGFX Breakaway Box 550 is a better choice thanks to its compatibility with a wider range of graphics cards. It’s a must if you want to use a high-end GPU in a non-reference design. When connected to an ultrabook, you will appreciate the charging capability. However, if you plan to use mainstream graphics cards, the less expensive eGFX Breakaway Box 350 will suit you well and fulfill your needs. I definitely recommend that you think twice about which dock to choose since it’s not a small investment, and you should also consider your future needs.

1-meter long Thunderbolt 3 cable

The cable has the same 40 Gbps throughput as 0.5 m version, but it only supports USB 2.0 and 60 W charging. The cable supplied with both eGFX Breakaway Box models supports USB 3.1 and 100 W charging, which makes it more flexible, but if you only care about the connection to the dock, the 1 m version will do its job 100%.

When purchasing the eGFX dock, I recommend that you get the 1 meter Thunderbolt 3 cable from Sonnet as well. As stated earlier, the docks come with a 0.5 m cable as standard. However, it’s really short and when using the dock it really limits its flexibility. With a 1 m cable it’s much more bearable. It allows you to set the dock in better place, and you are not as limited with the placement of the notebook or other client, either.

Price and availability

Since the release of our review of the eGFX 350 the availability of Sonnet products in Slovakia and Czechia has improved. You can purchase the docks in ČR on DTPobchod.cz.

The prices haven’t really changed, eGFX 350 still costs 9990 kč (390 €), eGFX 550 has got a little bit cheaper at 11250 kč (440 €). There’s new distributor in Slovakia – Centron Slovakia. The docks have better availability once again which is definitely a good news.

Sonnet eGFX Breakaway Box 550
9.4 Hodnotenie redakcie

better compatibility
more powerful


higher price

Sonnet eGFX Breakaway Box 550 is more expensive but improved version of eGFX Breakaway Box 350. Thanks to the more powerful PSU it can power high-end graphics cards like GTX 1080 Ti. You can also count with 87 W charging which will work with most of the current notebooks and ultrabooks. The looks and other aspects of the docks are the same.

The Sonnet eGFX Breakaway Box 550 receives our Gold award for great build quality, improved compatibility and good price.

We thank Sonnet for providing us with review units of eGFX Breakaway Box 350 and 550, company Asus for graphics card  GTX 1080 Ti Strix OC MSI for graphics card GTX 1060 Armor 3G and Lenovo for ThinkPad X1 Carbon.


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