You will need a USB cable

Do USB 3.0 connections require USB 3.0 cables?

If you are new to the world of USB 3.0 then you may have many questions about the cables you can and / or should use with USB 3.0 enabled devices. With this in mind, today's SuperUser question and answer article helps a curious reader to get to know the "advantages and disadvantages" of USB 3.0.

Today's Q&A session is hosted by SuperUser - a division of Stack Exchange, a community-driven grouping of Q&A websites.

Photo courtesy of Xiao Zong Zong (小宗 小宗 - Flickr).

The question

SuperUser Reader Xavierjazz would like to know if USB 3.0 connections require USB 3.0 cables to achieve their full speed potential:

Do USB 3.0 connections require USB 3.0 cables to achieve USB 3.0 speeds? Does a USB cable support a USB 3.0 device?

Do USB 3.0 connections require USB 3.0 cables to reach their full speed potential?

The answer

SuperUser contributors Steven and fixer1234 have the answer for us. First Steven:

A USB 3.0 cable is required for USB 3.0 speeds, but any USB cable connects.

Source 1: USB [Wikipedia]

SuperSpeed ​​(USB 3.0) is only supported by USB 3.0 and newer interfaces and requires a connector and cable with additional pins and wires, usually identified by the blue inserts in the connectors.

Source 2: USB 3.0 super speeds [USRobotics]

USB 3.0 cables can be used with 2.0 devices and ports if the connector types match (no B-male or B-micro connectors), but the transfer rate will reset to 2.0.

Source 3: Are there any differences between USB 3.0 cables? [UserBenchmark]

To get USB 3.0 speeds, you need a special USB 3.0 cable. Yes, USB 3.0 cables are different. Although you can connect a USB 3.0 device using a USB 2.0 cable, you will need to rewire any existing cables to achieve full USB 3.0 speed. USB 3.0 cables have more internal wires, are usually blue, and are noticeably thicker than the old USB 2.0 cables. We found this out the hard way in the group test with USB sticks.

Followed by the answer from fixer1234:

You cannot achieve USB 3.0 speeds without a USB 3.0 cable. However, speed isn't the only problem.

A USB 2.0 cable (at USB 2.0 speed) will work with some, but not all, USB 3.0 devices. There are at least three important differences in cable design between the two standards.

Related to speed:

  • USB 3.0 cables have nine internal conductors versus four in USB 2.0 cables.

Four of the nine inner conductors match the USB 2.0 configuration (two for the power supply and two for the signal). Connecting a USB 3.0 device with a USB 2.0 cable uses these conductors and works like a USB 2.0 device.

The other five are signal conductors used for the communication method that USB 3.0 Super Speed ​​provides. A good general description can be found here: USB 3.0 [Wikipedia]

  • USB 3.0 cables are limited to three meters, USB 2.0 to five meters.

(Note that this is a practical limit.) The cable can be of any length according to all electrical requirements in the specification. The three meter limit is based on the maximum allowable losses using the largest recommended wire size to allow the cable to be flexible. Specification document [zip file - USB.org]

In connection with power:

  • A USB 2.0 cable may not work with a high-current USB 3.0 device.

Some USB 3.0 devices use more power than USB 2.0 devices. The current conductors in USB 3.0 cables must be able to carry 900 mA compared to 500 mA in USB 2.0 cables.

Further information on USB 3.0 and 2.0 can be found here: USB 2.0 vs. USB 3.0 [Diffen]


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