A first look at USB 3.1 performance
A new generation of USB devices is upon us.
A year and a half after the completion of the USB 3.1 spec, motherboards supporting the new standard are turning up in e-tail stocks. Also known SuperSpeed Plus, USB 3.1 promises a sizable performance increase over the previous generation.
It doubles the signaling speed from 5Gbps to 10Gbps, and it also changes the line encoding scheme from 8b/10b to 128/132b, meaning that only four bits out of every 132 (as opposed to two out of every 10) are sacrificed to encoding overhead. The result is a jump in maximum effective transfer rates from 500MB/s to 1.21GB/s—at least in theory.
USB 3.1 also introduces Type-C connectors and cables. Type-C connectors are reversible, so you can plug them in upside down without worrying about that whole USB quantum superposition mess. Type-C cables support Alternate Mode, as well, which allows them to carry DisplayPort audio and video alongside USB 3.1 data and as much as 100W of power. Some have called USB 3.1 Type-C a Thunderbolt killer, and it’s not hard to see why.
Today, we’re going to take our very first look at some USB 3.1 gear. Asus has supplied us with a drive enclosure and a matching motherboard, which will help us gauge the kinds of performance gains users can expect.
According to Asus, our USB 3.1 enclosure is a “prototype for testing,” not a retail product. It doesn’t look half bad, though:
The enclosure features one of the new Type-C ports along with an old-school Micro-USB connector. The former is for data, while the latter supplies power to the enclosure. If this were a retail device, a single Type-C port would theoretically be enough for both power and data.
There’s not much to say about the Type-C connector itself, except that it’s predictably painless to use. Apple’s Lightning connector still feels sturdier and smoother to insert, but the Type-C plug remains a big improvement over, well, pretty much all standard USB connector designs.
I bet some of you were expecting the enclosure to conceal a 2.5″ SSD. Guess again! This puppy actually houses two mSATA drives running in RAID-0 mode. That arrangement should enable peak transfer rates greater than the mSATA interface’s 6Gbps maximum.
Asus sent us the enclosure with a couple of Samsung’s 840 EVO 250GB solid-state drives. The RAID-0 config results in a 500GB volume that should be faster than either drive on its own.
The drive enclosure wouldn’t do us much good without a motherboard capable of harnessing USB 3.1’s higher speeds. Asus’ Z97-A/USB 3.1 fills that role. As its name suggests, this board is a USB 3.1-infused successor to the Z97-A we reviewed last year. It has a similar layout and feature set, but its rear cluster sports a couple of teal-colored SuperSpeed Plus Type-A ports. (The original Z97-A had two USB 2.0 ports in the same spot.)
Because they’re Type-A, the new ports are backward-compatible with older USB devices. However, that advantage comes with a tradeoff: no support for Type-C’s Alternate Mode or 100W power delivery. According to Asus, these USB 3.1 Type-A ports are limited to 4.5W.
Since Intel’s Z97 chipset lacks built-in support for USB 3.1, the new ports are backed by an ASMedia ASM1142 controller. The ASM1142 can be fed by either one PCIe Gen3 lane or two PCIe Gen2 lanes. Asus uses the latter arrangement on the Z97-A/USB3.1.
The two PCIe Gen2 lanes provide the ASMedia controller with 10Gbps of bandwidth, but there’s a catch. Actually, two catches. First, that 10Gbps is shared between the two USB 3.1 ports. Second, because PCIe Gen2 uses 8b/10b encoding, maximum effective transfer rates are limited to 1GB/s, somewhat shy of SuperSpeed Plus’ 1.21GB/s theoretical maximum. Using PCIe Gen3 wouldn’t address the second catch, since a single Gen3 lane would deliver 8Gbps with 128/130b encoding, for an effective 985MB/s.
Partly because the Asus drive enclosure doesn’t support either TRIM or secure erase, and partly because we were short on time, we forewent our usual storage benchmark suite. Instead, we simply ran CrystalDiskMark, which measures sequential read and write speeds. That ought to give us a nice, at-a-glance overview of USB 3.1’s potential.
For our testing, we fired up Asus’ AI Suite software and enabled “Turbo” mode for the USB 3.1 controller. “Turbo” mode enables the USB attached SCSI protocol, which boosts transfer speeds by “eliminating most of the round trip delays between command phases and by utilizing a multi-tasking aware architecture that [speeds up] multiple transfers,” according to Asus. Here are the results:
Simply switching the drive enclosure from a USB 3.0 port to a USB 3.1 one boosts sequential read and write performance by a good 75-78%. 4K random write speeds almost triple, too, although that gain may be attributable partly to differences between the Z97 chipset’s native USB 3.0 implementation and the ASMedia USB 3.1 controller.
Either way, these speeds are impressive. Yes, it does take two SSDs running in RAID-0 mode to reach them. But keep in mind that newer M.2 SSDs can surpass the SATA interface’s 6Gbps limit, and nothing is stopping hardware makers from devising USB 3.1 enclosures for those.
So, when can you get your hands on some USB 3.1 hardware yourself?
The motherboard we tested today is already available at Newegg for $159.99. The same e-tailer also sells Asus’ Z97-PRO(Wi-Fi ac)/USB 3.1 and Z97-Deluxe/USB 3.1, which are similarly equipped with USB 3.1 Type-A ports. If you need cables, Newegg has you covered there, as well.
As for USB 3.1 devices to plug into those boards, I don’t see any listed yet—but Asus did provide us with this handy list of upcoming products:
|Manufacturer name||Product category||Product name||Availability|
|AKiTiO||USB 3.1 device||Neutrino Bridge USB3.1||March 2015|
|USB 3.1 device||NT2 U3.1||March 2015|
|AVLAB Technology SIIG||USB 3.1 to 2.5-inch||USB 3.1 to SATA 2.5-inch Enclosure||April 2015|
|USB 3.1 to 2.5-inch||USB 3.1 to SATA 2.5-inch Enclosure Pro||Q2-Q3 2015|
|USB 3.1 to 3.5-inch||USB 3.1 to SATA 3.5-inch Enclosure||April 2015|
|GODO||2.5-inch USB 3.1 enclosure||GD25602 2.5-inch USB3.1 HDD Enclosure||March 2015|
|2.5-inch USB 3.1 enclosure||GD25702 2.5-inch USB3.1 HDD Enclosure||March 2015|
|2.5-inch USB 3.1 enclosure||GD25611 2.5-inch USB3.1 HDD Enclosure||March 2015|
|HighPoint Technologies, Inc||USB 3.1 device||RS3111A||March 2015|
|USB 3.1 device||RS3112A||April 2015|
|Iomaster||2-port host card||IOT-U31A3||March 2015|
|SATA 2.5 enclosure||IOT-3125A3||March 2015|
|USB 3.1 to SATA 2.5 & 3.5 adapter||IOT-3123A3||April 2015|
|USB 3.1 to MSATA & M2 SSD enclosure||IOT-U31NF||March 2015|
|Minerva Innovation Company||3.5-inch SATA to USB 3.1 enclosure||3.5-inch SATA mSATA x 2 and M.2 x 2 to USB 3.1 Adapter (Type B)||March 2015|
|2.5-inch SATA to USB 3.1 enclosure||2.5-inch SATA mSATA SSD x 2 to USB 3.1 External Enclosure (Type-C x 2)||March 2015|
|2.5-inch SATA to USB 3.1 enclosure||2.5-inch SATA M.2 SSD x 2 to USB 3.1 External Enclosure (Type-C x 2)||April 2015|
|Speed Dragon||USB 3.1 device||USB 3.1 to SATA 6G cable adapter||March 2015|
|USB 3.1 device||USB 3.1 PCI-Express add-on card||March 2015|
|USB 3.1 device||USB 3.1 PCI-Express add-on card||March 2015|
|USB 3.1 device||USB 3.1 to dual SATA 6G hard drive enclosure||April 2015|
|Super Talent Technology Corporation||USB 3.1 device||USB3.1 Portable SSD||May 2015|
|Sunrich Technology||Adapter||U-1040 USB 3.1 to SATA 6G Adapter||March 2015|
|Adapter||U-1050 USB 3.1 to SATA 6G Adapter||April 2015|
|Hub||U-1060 USB 3.1 4-Port Hub||TBA|
|Hub||U-1070 USB 3.1 7-Port Hub||TBA|
|Docking station||U-1080 USB 3.1 Docking Station||TBA|
|Docking station||U-1090 USB 3.1 Docking Station||TBA|
|UNITEK||PCI Express to 2 Ports USB 3.1 (Type-A x 2)||Y-7305||March 2015|
|PCI Express to 2 Ports USB 3.1 (Type-A x 1, Type-C x 1)||Y-7306||March 2015|
|USB 3.1 to SATA6G enclosure||Y-3363||April 2015|
|USB 3.1 to SATA6G Docking station||Y-3605||April 2015|
|USB 3.1 to 2.5-inch Dual SATA6G enclosure (Type-C)||Y-3364||April 2015|
|USB 3.1 active extension cable||Y-3001||June 2015|
I don’t see that nifty Type-C thumb drive Adata showed us at CES a couple months back, but I’m sure it’s coming, too.
Other motherboard makers are also jumping on the USB 3.1 bandwagon. Both ASRock and MSI have boards with USB 3.1 Type-C ports in the pipeline, and Biostar is cooking up a Z97 mobo with USB 3.1 Type-A ports. Then there’s Apple, whose next MacBook Air laptop is rumored to feature a single USB 3.1 Type-C connector that splits power, data, and audio/video output duties.
In short, USB 3.1 is here, and there’s plenty more where it came from. Given the encouraging nature of our performance results and the awesome reversibleness of the Type-C connector, that’s cause for celebration.