USB-C vs. USB 3.1: What’s the difference?
USB-C vs. USB 3.1: What’s the difference?
With the launch of the Apple MacBook and Google’s Chromebook Pixel, USB-C (also called USB Type-C) and the accompanying USB 3.1 standard are both hitting market somewhat earlier than we initially expected. If you’re curious about the two standards and how they interact, we’ve dusted off and updated our guide to the upcoming technology. The situation is more nuanced than it’s been with previous USB standard updates — USB 3.1 and USB Type-C connectors may be arriving together on the new machines, but they aren’t joined at the hip the way you might think.
USB Type-C: Fixing an age-old problem
The near-universal frustration over attempts to connect USB devices to computers has been a staple of nerd humor and lampooned in various ways until Intel finally found a way to take the joke quantum.
USB Type-C promises to solve this problem with a universal connector that’s also capable of twice the theoretical throughput of USB 3.0 and can provide far more power. That’s why Apple is pairing up Type-C and USB 3.1 to eliminate the power connector on the MacBook. It’s a goal we agree with, even if we’re less thrilled with the company’s decision to dump USB ports altogether with that single exception. Google’s approach, in providing two USB-C and two regular USB 3.0 ports, is obviously preferable, even though it adds a bit of bulk to the machine.
Type-C connectors will be shipped in a variety of passive adapters (an earlier version of this story erroneously asserted that such cables would not be available, Extremetech regrets the error). The spec provides for passive adapters with USB 3.0 / 3.1 on one end and USB Type-C on the other.
USB-C, USB 3.1 not always hooked together
The Type-C plug can be used with previous standards of USB, which means manufacturers don’t automatically have to adopt expensive 3.1 hardware if they want to include it in mobile devices. Apple, to be clear, is offering USB 3.1 on the new MacBook, though the company hasn’t disclosed which third party vendor is providing the actual chipset support.
The disconnect between USB 3.1’s performance standard and the USB Type-C connector is going to inevitably cause confusion. One reason the shift from USB 2.0 to 3.0 was relatively painless is because coloring both the cables and plugs bright blue made it impossible to mistake one type of port for the other.
The upside to decoupling USB 3.1 from USB-C, however, is that companies can deploy the technology on mobile phones and tablets without needing to opt for interfaces that inevitably consume more power. Then again, some might argue that this would be a moot point — the USB controller can be powered down when it isn’t active, and when it is active, the device should be drawing power off the PC or charging port anyway. Heat dissipation could theoretically remain a concern — higher bandwidth inevitably means higher heat, and in devices built to 3-4W specifications, every tenth of a watt matters.
If I had to bet, I’d bet that the 100W power envelope on USB 3.1 will actually be of more practical value than the 10Gbps bandwidth capability. While it’s true that USB 3.1 will give external SSD enclosures more room to stretch their legs, the existing standard still allows conventional mechanical drives to run at full speed, while SSDs can hit about 80% of peak performance for desktop workloads. It might not be quite as good, but it’s a far cry from the days when using USB 2.0 for an external hard drive was achingly slow compared to SATA. Signal overhead is also expected to drop significantly, thanks to a switch to a 128-bit and 132-bit encoding scheme, similar to that used in PCI-Express 3.0.
The ability to provide 100W of power, as opposed to 10W, however, means that nearly every manufacturers could ditch clunky power bricks. There would still be concern about ensuring that connect points were sufficiently reinforced, but provided such concerns can be accounted for, the vast majority of laptops could switch over to the new standard. Hard drives and other external peripherals could all be powered by single wires, as could USB hubs for multiple devices.
The higher bandwidth is nice, and a major selling point, but the flippable connector and the power provisioning will likely make more difference in the day-to-day reality of life. As forcompetition with Intel’s Thunderbolt, USB 3.1 will continue to lag Intel’s high-speed standard, but as bandwidth rises this gap becomes increasingly academic. At this point, it’s the features USB doesn’t allow, like RAID and TRIM, that matter more than the raw bandwidth does in most cases.
Apple’s MacBook will be first out the door with USB 3.1 and USB-C support, with vendors scurrying to match the company on both counts. LaCie has announced a new revision of itsPorsche Design Mobile Drive that takes advantage of the Type-C connector, but only offers USB 3.0. It’s going to take time for the 3.1 spec to really show up on peripheral devices, even those that adopt the USB-C cable. Motherboard support outside the Apple MacBook is probably 4-5 months away, though the first peripheral cables should be available well before that point.
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