Thunderbolt to Your Wallet

The Sonnet Fusion Thunderbolt 3 is by far the fastest external storage device we have tested to date. Earlier this year we had been impressed by Samsung's Portable SSD T3 series in spite of some performance shortcomings, but in comparison the Fusion Thunderbolt 3 was about five times faster in our tests.

It is worth noting that the Fusion Thunderbolt 3 could be even faster than we were able to make it go. Sonnet claims read speeds of up to 2.1 GB/s and write speeds of 1.55 GB/s. Since we maxed out at around 1.3 GB/s read and 1.2 GB/s write, we suspect the Razer laptop may have been the bottleneck leading to the limited performance. Though still a spectacular result for the Sonnet Fusion, it does bring the concern that not all Thunderbolt 3 hosts can be considered the same.

Sonnet has done a nice job, creating a highly practical and durable enclosure for the Fusion. They could have certainly made the enclosure much smaller but this may have had an effect on cooling and possibly made it less resistant to abuse. The replaceable Thunderbolt cable is nice, though the process is less convenient than we would have liked.

The only other concern is price. Thunderbolt products have always come at a premium, and this latest iteration is no different. Despite very limited support (or perhaps because of it) Sonnet are still charging a small fortune for the Fusion – $800 for 512GB.

Consider that a standalone Samsung SM951 NVMe 512GB SSD costs $370. Meaning that the SSD inside the Fusion accounts for 46% of the total drive cost, while the other half gets gets you an aluminium enclosure, a half meter Thunderbolt 3 cable, and the Thunderbolt 3 controller. It seems a bit hard to justify, but that is the price of extreme performance on portable storage.

To draw a few comparisons, the LaCie 1TB Chromé USB 3.1 Type-C External SSD costs $1500 and it's considerably slower than the Fusion Thunderbolt 3. That said, although at a somewhat higher price point, the Akitio Thunder 3 1.2TB costs $1280 making it almost 30% cheaper per GB. It is, however, much larger and requires external power.

Something the Akitio drive has that is sorely missed on the Fusion Thunderbolt 3 is a second Thunderbolt 3 Type-C port for pass through. This means while the Akitio can daisy-chain up to half a dozen Thunderbolt devices, the Fusion Thunderbolt 3 hogs an entire port all to itself. With Thunderbolt 3 ports at a premium right now, having a device that can't share the port is far from ideal.

Overall, the Sonnet Fusion Thunderbolt 3 PCIe Flash Drive 512GB is a sleek, compact external drive capable of truly impressive performance


Pros: The fastest external storage device we've ever tested. Pocket-sized, well built. No power supply/power cable needed. Passively cooled. Replaceable Thunderbolt cable.

Cons: Expensive. No Thunderbolt 3 pass-through.