Other World Computing has long been a source for nifty Mac accessories, so when it released the Mercury Helios PCIe Thunderbolt Expansion Chassis, we were happy to receive one for review.
So, what exactly is a PCIe Thunderbolt Expansion Chassis, and why should you care? Good questions. The Helios system uses a Mac's Thunderbolt port to create an extension to the PCIe bus inside the Mac.
This lets you expand the capabilities of your Mac by adding PCIe cards, such as video capture and processing cards, audio capture and processing cards, and high-performance Ethernet cards; Fibre Channel, FireWire, USB, eSata, SAS, and other I/O ports; and of course storage systems, such as the 240 GB Mercury Accelsior PCIe SSD that was included with our review version of the Mercury Helios.
The Helios system gives an iMac, MacBook Pro, MacBook Air, or Mac mini expansion capabilities similar to the ones that only the desktop Mac Pro currently provides, in a package that isn't much bigger than an external hard drive
Reviewer’s note: The Mercury Helios PCIe Thunderbolt Expansion Chassis now comes equipped with the newer Mercury Accelsior E2 PCIe card that features the same internal SSDs and new external eSATA ports.
OWC Mercury Helios Specifications and Tear Down
The Mercury Helios system is an external case that measures roughly 8-¾ x 5-3/8 x 2-½ inches. Opening the case requires removing four small Phillips head screws.
Kudos to OWC for using standard screws; many manufacturers use screws that require a special tool to remove them.
Inside the case are two PCBs (Printed Circuit Boards). The main board contains the PCIe and Thunderbolt controller; a small daughter card houses a PCIe slot that will accept a third-party expansion card. The review unit delivered to us here at About: Macs was pre-populated with the Mercury Accelsior PCIe SSD card.
The case also contains a small variable speed fan and a PCIe single-slot card cage to support any expansion card you choose to install. What's missing is an internal power supply. OWC chose to power the Helios system from an external power supply, which means that a small fan can take care of cooling, cutting down on noise.
The back panel contains two Thunderbolt connectors, allowing you to daisy chain additional Thunderbolt devices, as well as a 12 VDC connector to power the device. The front panel contains a small LED that indicates power status; the small fan is mounted at the front as well.
The OWC Mercury Helios is well constructed, with an all-metal case that is easy to disassemble and, perhaps just as important, reassemble.
The Helios system can accept a single half-length, single-width PCIe 2 card with up to 8 lanes (8x speed). OWC includes a list of compatible PCIe cards that it has tested and are known to work without issues with the Helios PCIe expansion chassis. There are probably additional expansion cards that will work; OWC just hasn't had a chance to test them all yet.
That's not to say that every expansion card will work. Cards that require a good deal of power obviously won't work with the Helios system's small power supply. In addition, cards that require drivers to be loaded may or may not work, especially if they don't support the Thunderbolt Tunnel capability. If you want to use a PCIe expansion card that's not on OWC's list, check with the manufacturer to see if it has Thunderbolt-aware drivers.
Installation and Use
Because our Mercury Helios review unit came with the Mercury Accelsior PCIe SSD card, we didn't have to install an expansion card for testing. However, as noted in the section above, accessing the case and installing a PCIe 2 card is a simple task. Once you install the PCIe card, connecting the device to a Thunderbolt-equipped Mac is a simple matter of connecting power to the case and running a Thunderbolt cable between the Mercury Helios and your Mac.
One note about the Thunderbolt cable: you'll need to use a Thunderbolt-to-Thunderbolt cable. A Thunderbolt to Mini DisplayPort cable, which looks almost exactly the same, won't work. To save yourself some aggravation, make sure you have the correct cable on hand.
Once the cabling is taken care of, using the Helios is just a matter of turning on your Mac. The Helios has no power switch. It will sense that the Thunderbolt port has become active and turn the unit on. Likewise, when you power your Mac off, the Helios will shut down as well.
In addition to the power-sensing feature of the Helios, it is also fully hot swappable; you can disconnect and reconnect the Thunderbolt cables without causing problems with either the Helios unit or your Mac. That being said, I don't advise anyone to plug or unplug any device willy-nilly, whether it's hot swappable or not.
I chose to connect the Helios expansion chassis to a 2011 MacBook Pro. Once the cables were connected, I booted up the MacBook Pro and the Helios system came to life. After the Mac desktop appeared, the Mercury Accelsior PCIe SSD mounted on the desktop.
Testing and Benchmarks
One of the questions that interested me is how well the SSD card in the Helios performs. Many Mac users need or desire a faster system. An SSD is one way to boost a Mac's performance, but for many Macs, SSD options are limited. In most cases, you must decide whether or not to purchase an SSD when you purchase your Mac; adding an internal SSD later is a difficult task.
External SSDs are certainly usable on newer Macs with USB 3 ports, but the Thunderbolt port is a much better choice, especially if you're a real speed freak, and you plan to configure one or more SSDs in a striped RAID 0 array.
So, with performance as a backdrop, I set out to see how well the Mercury Accelsior PCIe SSD would perform in the Helios expansion chassis.
I started by reformatting the Accelsior SSD, and then installed OS X Mountain Lion on the SSD. The first test was an easy one; is the SSD mounted in the Helios expansion chassis bootable? The answer was a resounding yes. I was concerned that the Helios's power-sensing system, which monitors the Thunderbolt connection, might prevent the expansion chassis from waking up in time to be used as a boot device, but in repeated tests, I didn't run into any problems with the power-on system.
I then loaded up a few of my favorite bench test utilities to see how fast the SSD performed over the Thunderbolt connection. Drive Genius 3's Benchtest utility produced the following test results.
Drive Genius 3 Test Results
- Peak Random Write: 506.658 MB/s
- Peak Random Read: 571.051 MB/s
- Peak Sustained Write 508.712 MB/s
- Peak Sustained Read 575.788 MB/s
I also ran Blackmagic's Disk Speed Test, which looks at sustained write and read speeds using standard video frame sizes instead of data block sizes. This provides a very good idea of how a drive will perform when used for video capture and editing tasks.
Blackmagic Disk Speed Test results
- Write: 472.2 MB/s
- Read: 616.8 MB/s
The bench test results are certainly impressive, with no indication that the Thunderbolt interface has any performance effect on the PCIe expansion chassis in the Mercury Helios system. To put the performance in perspective, according to Blackmagic's Disk Speed test, you could blast up to 116 (read) or 88 (write) streams of HD 1080p through the Helios system without breaking a sweat.
OWC Mercury Helios - Final Thoughts
Let me start off by saying that I'm going to be sad to return the Helios system to OWC. It brought our MacBook Pro to performance levels we've never seen before. The MacBook Pro performed like a brand-new Mac with the latest and fastest SSDs installed.
But that only scratches the surface of what the Helios system can do. Sure, having the Mercury Accelsior SSD installed in the Mercury Helios system created one of the highest performance drives we've ever connected to our MacBook Pro. And while that alone may be more than enough reason to consider the expansion chassis, its ability to bring specialty PCIe cards to a Thunderbolt-equipped Mac may prove to be an even better reason to pick up one or more of these devices. Who doesn't want to be more productive?
If you're a video or audio producer looking to outfit a portable studio, or add capabilities to an existing Mac-based system, you should be looking at the Mercury Helios PCIe Thunderbolt Expansion Chassis.
Likewise, if you need a way to add high performance storage involving an SSD, SAS, SAN, or other storage solution, then this may be just the product you're looking for to build a high performance storage system around.
Because of all the possibilities the Mercury Helios system provides, I'm having a hard time boxing the unit up and sending it back. That may be one of the best indications of how well designed this product is.
Disclosure: Review samples were provided by the manufacturer. For more information, please see our Ethics Policy.