Technology Explained

USB 3.0: Everything You Need to Know

Tina Sieber 15-07-2010

Within the past 14 years, the Universal Serial Bus (USB) has become the standard interface to connect devices to a computer. Whether it’s an external hard drive, a camera, the mouse, a printer, or a scanner, the physical connection to transfer data between devices generally is a USB cable. The interface is indeed universal.


USB technology has been under development since 1993. The first official definition, USB 1.0, was introduced in 1996. It provides a Low-Speed transfer rate of 1.5 Mbps for sub-channel keyboards and mice, and a Full-Speed channel at 12 Mbps. USB 2.0, which came in 2001, made a leap to Hi-Speed transfer rates of up to 480 Mbps. In 2010, USB 3.0 has finally hit the market.

So what can you expect from USB 3.0 and how will it affect you?

USB 3.0 Specifications

A number of changes have been implemented in USB 3.0 to satisfy the increased demands of external devices. Here is a quick USB technology overview:

  • Transfer Rate
    This new SuperSpeed interface provides realistic transfer rates of around 3,200 Mbps or 3.2 Gbps. The theoretical top signaling rate is at 4.8 Gbps.
  • Data Transfer
    USB 3.0 introduces full duplex data transfer. Two of five lanes are reserved for transmitting data, while another pair is dedicated to receiving data, meaning that USB 3.0 can read and write data simultaneously at full speed. Previous USB specifications did not support bi-directional data transfer.
  • Power
    The unit load has been increased to 150 mA and a configured device can draw up to six unit loads, which adds up to 900 mA. This exceeds USB 2.0 by 80% and leads to faster recharging or powering of more than four devices from a single hub. In addition, the minimum device operating voltage was dropped from 4.4 V to 4 V, which saves energy.
  • Power Management
    USB 3.0 suspends device polling, which is replaced by interrupt-driven protocol. As a result, idle devices won’t experience a power drain since a signal from the device is required to initiate data transfer. With USB 2.0 the host controller used to look for active transfers, slowly draining power. Briefly, USB 3.0 supports idle, sleep, and suspend states, as well as link-, device-, and function-level power management (Wikipedia).
  • Physical Appearance
    The above described specifications are also represented in the physical appearance of USB 3.0. While the cable was previously described to be thicker because it contains four more wires than USB 2.0, this appears not to be the case now. The plug, however, is a dead giveaway for USB 3.0. It contains an additional set of connectors, as illustrated in the image below.

usb technology

The Good News

New technology is very exciting. But what does it mean? Will you still be able to use your old USB hardware? How will the new USB technology affect your everyday life? What are the benefits?

  • Compatibility
    USB 3.0 is backwards compatible with USB 2.0. So whether you get a new USB 3.0 device or a new computer that supports USB 3.0, your old device will be able to communicate with the new interface. Naturally, it will do so at the old USB 2.0 speed. However, you won’t be able to use a USB 3.0 cable to connect a USB 2.0 device.
  • Transfer Rate
    Now I bet all this Megabit and Gigabit per second numbers sound impressive, but what does it actually translate to? Well, let me give you an example. With USB 3.0 you could transfer a 10 GB file from your computer to an external drive in approximately 25 seconds. With USB 2.0 this would take more than five minutes.
  • Benefits
    The devices that will benefit most from USB 3.0 are those that already outspeed USB 2.0, including HD webcams, Blu-Ray drives, or some external hard drives.
  • Support by Operating Systems
    Windows Vista, Windows 7, and Linux already support USB 3.0. Mac is expected follow. Given its age, Windows XP will probably not receive an update to support the new interface.

The Bad News

I was tempted to report that there is no bad news, but that’s not true. Let’s say bad news is minimal.

  • Cable
    The maximum cable length USB 3.0 supports is reduced to approximately three meters, opposed to five meters with USB 2.0. However, using hubs, the maximum length can be extended to 18 meters.
  • Speed Limit
    Naturally, not all devices will be able to make use of the increased speed in USB 3.0. Magnetic hard drives for example, are limited by their RPM and the corresponding read/write speed. Hence, USB 3.0 will not unfold its full beauty until computers are equipped per default with faster hardware, such as solid state drives. But we all know how speedy progress is in the IT world. Give it a year or two and you will be able to fully benefit from USB 3.0.

Feel like you need more information? Computerworld has an excellent USB 3.0 review (USB 3.0: The new speed limit), including tests of currently available USB 3.0 hardware. Are you craving for even more in depth information? Check out this article at Tech Republic: 10 things you should know about USB 2.0 and 3.0. And have a look at Everything USB’s Super Speed USB 3.0 FAQ.

Now aren’t you looking forward to switching to USB 3.0? And if you have already been using a USB 3.0 device, please let the rest of us know how it feels!

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  1. wayne
    January 21, 2018 at 8:56 am

    Can I connect one USB 3.0 active extension cable to another one ?

    • Tina Sieber
      January 22, 2018 at 5:17 am

      I'm pretty sure you can, though I'm not sure whether or not that would have a detrimental effect on your data transmission quality.

  2. Rudolf Zlabinger
    June 3, 2017 at 4:57 am

    I use an external drive with USB 3,0 specification, reducing thereby a full backup time (with data pointed to from my personal folder, so I get the private data backupped twice, as the data harddrive is included in the System imge also) to the empty drive in 1 hour. Windows 10 by Windows 7 backup functionality.

  3. PN
    October 17, 2016 at 4:30 pm

    can i connect/transfer files between two PC using USB 3.0 ??

  4. Michael Davison
    September 20, 2016 at 8:21 pm

    I've had a HP Deskjet 450 printer for about 3 years. It's really handy for taking around with me.
    It operated fine on my Dell XPS until I upgraded to Windows 10.
    Every time I try to print, I get an error message saying it can't print. I know there's nothing wrong with the printer, as it works fine on an old laptop with Windows XP.
    I just ran the troubleshooter and it said the 'older' device won't work with USB 3.
    Why did it work before I upgraded to Windows 10? Is there any way to downgrade one of the USB ports to USB 2, or is it the hardware that makes it USB 3?

    Any advice would be appreciated or I will have to take my ancient XP laptop with me if I need to print away from home.

    • Tina Sieber
      September 21, 2016 at 12:14 pm

      Have you checked the HP website for a Windows 10 driver for this printer? USB 3 should be downwards compatible with USB 2 devices. This sounds like you need to update the printer. You might even have to downgrade the printer in case Windows 10 decided to install a newer one.

      Check this guide: //
      And do let us know what worked in case you're able to fix the issue. Thank you in advance, Michael!

  5. Anonymous
    May 21, 2016 at 3:03 pm

    I have two different brands of USB TV Tuner devices, both of which which work on one Win8 laptop but not a second also Win8 laptop.

    The only difference is that the the first laptop has 2 x USB2 ports and the second laptop has 1 x USB3 and 1 x USB2 ports. I am connecting the devices (one at a time) to the USB2 port, of course.

    It is "recognised" and comes up fine in the Device Manager, and works immediately on the laptop with the 2 x USB2 ports, but the software hangs when asked to scan for TV stations on the laptop with the USB2 port and the (unused) USB3 port.

    I've reset both laptops back to clean Factory settings several times, and this happens continually.

    I suspect the USB3 port's device driver must be affecting this, even though the device is connected to the USB2 port.

    How can I identify the USB3 ports in Device Manager so I can disable them and test if the Tuner will work then?

    • Tina Sieber
      June 1, 2016 at 1:15 pm

      Skris, have you been able to solve this in the meantime?

      You could try to disable the USB 3.0 host controller in the device manager under Universal Serial Bus controllers.

      You could also try connecting the tuner card to the USB 3.0 port; it should still work.

      Did you check the manufacturer of the laptop for updated hardware drivers? I'd do that first.

  6. Atul S Wagle
    May 8, 2016 at 1:26 am

    Will a USB 2.0 connector support a USB 3.0 device

    • Tina Sieber
      June 1, 2016 at 1:11 pm

      Yes! And vice versa.

      However, the USB 3.0 device will only function at the max speed of the USB 2.0 connector.

      Same if you connect a USB 2.0 device to a USB 3.0 connector -- in that case the device only supports USB 2.0 speeds.

  7. Ben Mordecai
    July 27, 2010 at 6:50 pm

    There still could be a way to hack together a method for extending the cable length. I have seen folks use a USB to Ethernet repeater for making USB 2.0 travel long distances, so I would imagine that something similar could work with USB 3.0. We'll see...

    • Tina
      July 28, 2010 at 8:54 pm

      Thanks for sharing! Let us know if you come across a How To demonstrating the workaround.

      • Ben Mordecai
        July 29, 2010 at 6:02 pm

        Will do :)

  8. Brwndv07
    July 19, 2010 at 1:21 pm

    I remember the days when I use USB 1.0 when I was using Windows 98. I haven't used the latest version yet, but it would be great for more faster data transfer. The best thing it has is it is backwards compatible which was not in the case of USB 2.0. Though we are getting new advancements in world of computer applications, and computer technologies. It was great to expect what was the next.

  9. Brwndv07
    July 19, 2010 at 11:21 am

    I remember the days when I use USB 1.0 when I was using Windows 98. I haven't used the latest version yet, but it would be great for more faster data transfer. The best thing it has is it is backwards compatible which was not in the case of USB 2.0. Though we are getting new advancements in world of computer applications, and computer technologies. It was great to expect what was the next.

    • Tina
      July 20, 2010 at 3:15 pm

      USB 2.0 was not backwards compatible with USB 1.x? I'm pretty sure it was! I think the cable was the same and you could definitely use USB 2.0 devices on USB 1.x ports and vice versa.