The Mercury Helios 3S is an aluminium dual-port 85W charging Thunderbolt 3 expansion box with a dedicated DisplayPort 1.4 port for an 8K display. The Mercury Helios 3S accepts one PCIe (x16) slot for half-length, full-height, single or double-width cards. You can daisy-chain up to five additional Thunderbolt devices. OWC added the capability to install a U.2 Shuttle in the Helios 3S. My test unit came preconfigured with OWC Aura P12 Pro SSDs.
The U.2 Shuttle’s SSD’s are equipped with Triple-Level Cell (TLC) 3D NAND with SLC caching and a Phison E12 controller with 7% over-provisioning. To install and use the U.2 Shuttle, you will first need to install a carrier unit inside the Mercury Helios 3S that enables you to insert the U.2 Shuttle and swap it out. Unfortunately, with the U.2 shuttle carrier unit installed, the ability to install PCIe cards is lost. The U.2 Shuttle itself has a security lock with key and the enclosure has cooling ribs made for heat dissipation. The whole, when installed and ready, is robust and heavy. The power cable is even of the locking type.
I feared for the sound of the quite large cooling fan inside the Mercury Helios which is designed to cool PCIe cards as well as the U.2 Shuttle. Other OWC devices I tested in the past have often not been silent and I needed to bury them beneath my desk to keep the sound levels to a bearable level. That, I am very happy to say, is absolutely not the case with the Mercury Helios. The fan does make some noise but it requires you to put your ear at about 10cm from the unit to hear a faint low-pitched fan noise. It’s so quiet that I was able to just place it on my desk.
As for the U.2 Shuttle, it makes your workflow very efficient if you can just take it out with a day’s worth of images or videoclips and replace it with a fresh shuttle, ready to go for the next session with both of them ready for offloading at a later time.
The four Aura P12 NVMe SSDs inside the OWC U.2 Shuttle give you more RAID options than a dual drive enclosure or adapter card. With or without OWC’s SoftRAID software, you can put these in RAID 0, 1, 4, 5 or 1+0 (10). SoftRAID offers maximum volume capacity, optimum drive performance, data protection, and more and is ideal for anyone who needs to safely store and backup massive amounts of data, such as video editors, audio producers, photographers and graphic designers. The downside today is that it will not work with Big Sur.
If you don’t want to use the Mercury Helios 3S enclosure, by the way, you can use the carrier shuttle with U.2 port-equipped PCs and servers as well.
The performance of the 2TB U.2 Shuttle that I got for testing was great. I consistently got 2400MB/sec out of them. With the maximum capacity OWC offers in a ready-to-go U.2 Shuttle of 32TB, you won’t run out of space quickly.
There’s only one thing that I would have liked to be different about the Mercury Helios 3S and that’s the side where you mount and swap the Shuttle out. As it is now, it’s at the back where the cables are. It would have been easier if you could swap Shuttles from the front.
Admittedly, that’s a detail considering the unit’s build quality and its beneficial effects on your workflow. The Mercury Helios 3S with an U.2 interchange system retails at 279 USD. The U.2 Shuttle by itself without any NVMe modules installed costs 149 USD. My 2TB test Shuttle costs 449 USD.