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What's The Difference Between USB 3.1 Gen 1 And USB 3.1 Gen 2?

As you breeze through spec tables of new products, you’ll often find a mess of “USB” references. USB has become ubiquitous on devices from smartphones to massive gaming systems and all manner of miscellaneous consumer electronic devices, but a few years ago, we started seeing more types of USB emerge, which clouded and cluttered the connectivity world a bit. Specifically, people seem to get tripped up by the differences between USB 3.0, USB 3.1 Gen 1, and USB 3.1 Gen 2. Fortunately, it’s pretty simple to understand once you dig into the topic.

Forget About USB 3.0

First of all, USB 3.0 doesn’t really exist anymore. The USB Implementers Forum (USB-IF) chose to absorb the USB 3.0 spec into the USB 3.1 Gen 1 spec. Because of that, "The terms USB 3.0 and USB 3.1 Gen 1 are synonymous," a USB-IF representative told Tom's Hardware years ago when we first wrote about this issue. It’s essentially a clerical decision, as the USB-IF explained: "By incorporating USB 3.0, we're reducing the number of documents a developer needs to reference (we're talking hundreds and hundreds of pages of technical documents that developers have to parse through) and including all relevant information to ensure products are properly developed to be backwards compatible (protocol-wise, not related to cables/connectors)."

Therefore, if you see “USB 3.0” on a product, it’s probably a few years old. On anything made recently, you’ll see only “USB 3.1” or “USB 3.1 Gen 1” in its place. (There is one caveat to know, which we’ll discuss in a moment.)

Gen 1 Vs. Gen 2, And A Branding Issue

The difference between USB 3.1 Gen 1 and USB Gen 2 is as simple as this: Gen 1 offers 5Gbps speeds, whereas Gen 2 offers 10Gbps. Seriously, that’s it.

The USB-IF never intended for the those terms to be used in marketing materials, though. To help clarify the two different speeds of USB 3.1 and the various other protocols that can run over USB connectors (eg, Type-A and Type-C), the group created terminology and visual branding. For example, USB 3.1 Gen 1 is “SuperSpeed USB,” and USB 3.1 Gen 2 is “SuperSpeed USB+.” From there, the logos that OEMS were supposed to slap onto their products were designed to indicate if a port was capable of, for example, Power Delivery or DisplayPort.

We charted all of this out in this longer explainer, but it’s almost moot at this point. The industry never really picked up on the nomenclature and branding, so everyone just calls them “USB 3.1 Gen 1” and “USB 3.1 Gen 2.” Often, OEMs will add the speeds (5Gbps and 10Gbps, respectively) to their spec tables as a handy reminder for consumers. (SuperSpeed USB +, we hardly knew ye.)

  • AgentLozen
    The USB nomenclature was getting confusing even for ME: a Tomshardware sh*tposter. I was surprised that it could be explained so easily. Good article.
  • husker
    So... a rounded version number such as "1", "2", "3" is not enough. Instead, we need to use a decimal to distinguish 3.0 from 3.1. But the next version can't be 3.2 or 3.1.1, they have to name it "USB 3.1 generation 2". What is next, "USB 3.1 generation 2 first cousin"???
  • InvalidError
    @husker what's next is USB3.2 which sorts out the connector alphabit soup by mandating Type-C exclusively. The confusing speed standard verbiage still applies though - which of 'high speed', 'full speed' and 'super speed' stand for what speed? Only the most astute tech enthusiasts know the answer without looking it up. I hate obtuse marketing names. Gen-1/2 may not look pretty but it is simple and unambiguous.
  • groovyd
    USB is a joke... a committee and standards designed to confuse the sh*t of everyone, users and developers. And it isn't bad enough to develop for it you need to make sense of thousands of pages of nonsense but at the end of the day you have a box full of adapters and connectors that almost look the same but don't work together. Can we please just get a simple small unisex connector that plugs in either way both up or downstream and quickly and simply negotiate the protocol on connect? There is nothing high-tech about this, it could have been done when USB was introduced 100 years ago.
  • AnimeMania
    To me, the thing that is important is the color of the USB ports.

    Red, Orange or Yellow - has extra electrical power that does not shut down when the computer is turned off, used to charge devices like phones
    White - USB 1
    Black - USB 2
    Blue - USB 3.1 Gen 1
    Greenish Blue (Teal) - USB 3.1 Gen 2

    I am not sure if any motherboard manufacturers actually use the Blue/Teal colors to distinguish Gen 1 from 2
  • InvalidError
    20977730 said:
    it could have been done when USB was introduced 100 years ago.
    Part of the reason USB is the convoluted mess it has turned into today is because it was originally designed to be a low-cost replacement for the dozens of proprietary and legacy low-speed serial/parallel standards scattered all over the shop back in the day. A short while later, the original "full speed" 12Mbps turned out to be insufficient for many mainstream uses and we got USB2 aimed at displacing FireWire 400/800 in the medium-speed external interface arena.

    Much of this mess would have been avoided if USB had been designed with dedicated RX+TX pairs instead of time-shared multiplex over a single pair. But this wasn't compatible with USB's original objective of cheap cables, cheap connectors and cheap chips. So now we have those two dedicated RX and TX pairs, a bunch of auxiliary function pairs, the USB1/USB2 legacy pair and a couple of other things cluttering the type-C connector. Expensive connectors, expensive cables if you get fully wired ones, relatively expensive chips and circuit design if you want to support all functions at once.

    To hell with USB's original mission of being cheap and cheerful.

    I'd say we're overdue for replacing USB with an uncluttered external PCIe standard for high-speed external devices.
  • mlee 2500
    I want my USB ports to have a "turbo" button, so I can run slower if I want.
  • bachastain
    I want whatever drugs the USB engineers are taking. Seriously, I have never seen so many horrendous decisions come out of a single group before. For god's sake, apologize for the lapse in judgment and rename USB 3.1 Gen 2 to USB 3.2. Do it before you rot the brains of our deeply confused youth.
  • InvalidError
    20978406 said:
    For god's sake, apologize for the lapse in judgment and rename USB 3.1 Gen 2 to USB 3.2. Do it before you rot the brains of our deeply confused youth.
    USB3.2 has been defined as USB with Type-C connectors and speeds up to 20Gbps in July 2017. 10Gbps per lane, two lanes in each direction, including all of the backward-compatibility overhead for USB1/2/3.0/3.1.
  • alextheblue
    20977646 said:
    @husker what's next is USB3.2 which sorts out the connector alphabit soup by mandating Type-C exclusively.
    That doesn't actually fix the biggest issue. What does a particular USB-C port support? Power delivery? How much / what profile? Analog audio (for one-port phones to use analog headphones without an active adapter)? What alternate modes? HDMI, MHL, DP, Thunderbolt? Active or passive cable required? Who knows!

    I echo your sentiment that a PCIe based standard would be nice... as long as they can do longer than 1M passive cables (3.1 Gen 2).