Does a USB 3.0 connection require a USB 3.0 cord?

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Does a USB 3.0 connection require a USB 3.0 cord to reach USB 3.0 speeds (SuperSpeed)? Will any USB cord support any USB 3.0 device?

Xavierjazz

Posted 2015-07-07T15:14:54.043

Reputation: 7 993

Answers

95

The SuperSpeed transfer mode requires a USB 3.0 or higher cable. Earlier spec cables will still make a connection but at a slower rate.

Source 1: USB 3.0 - Wikipedia

The VBUS, D−, D+, and GND pins are required for USB 2.0 communication. The additional USB 3.0 pins are two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer; they are used for full duplex SuperSpeed signaling.

Source 2: USB 3.0 Super Speeds - USRobotics

USB 2.0 cables can be used with 3.0 ports but the transfer rate will fall back to 2.0

Source 3: Are USB 3.0 cables different? - Answers - UserBenchmark

Yes, to get USB 3.0 speeds, you need special USB 3.0 cables. Yes, USB 3.0 cables are different. Even though you can connect a USB 3.0 device via a USB 2.0 cable, in order to achieve full USB 3.0 speeds you need to re-wire any existing cabling. USB 3.0 cables are generally thicker because they have nine internal wires versus four on USB 2.0 cables.

Steven

Posted 2015-07-07T15:14:54.043

Reputation: 24 804

1Is there any substance in the "usually blue" claim? – Martin Argerami – 2015-07-07T23:33:18.057

23@MartinArgerami The usually blue applies to the plug (not the cable) - "Since USB 2.0 and USB 3.0 ports may coexist on the same machine and they look similar, USB 3.0 specification mandates appropriate color-coding and recommends that the Standard-A USB 3.0 connector has a blue insert (Pantone 300C color). The same color-coding applies to the USB 3.0 Standard-A plug" – DavidPostill – 2015-07-08T00:44:54.233

2There's a semi-official colour scheme I've noticed with sockets - USB 3's blue, USB 2.0 charging connectors (which are powered even when the PC they are off) are sometimes yellow. I'd rather look at the connectors for identification since I have blue usb 2.0/1.1 cables. – Journeyman Geek – 2015-07-08T04:16:18.013

3I understand that it's a quote, but I think that “will fall back...” should really be “will not magically increase”. – Carsten S – 2015-07-08T08:13:35.670

2For completeness, it's worth mentioning that 10GB USB3.1 ports (twice as fast as the 3.0 standard) are commonly a lighter shade of blue. I don't know if this is an official recommendation or not; but has held with most of the 3.1 board prototypes I've seen so far. – Dan is Fiddling by Firelight – 2015-07-09T00:49:18.430

@CarstenSchultz "magically increase" is probably a bit unfair; it's not an unreasonable assumption that the same cable could carry more data due to a better protocol/communication standard. Such a phenomenon has occurred multiple times for the simple copper wire used in telecoms. – RJFalconer – 2015-07-09T15:22:21.720

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A "USB 3.0 connection" requires a USB 3.0 cable.

Some USB 3.0 devices can be connected and operated as a USB 2.0 device (at USB 2.0 speeds), using a USB 2.0 cable. However, speed is not the only issue.

There are at least three important differences in cable construction between the two standards.

Related to speed:

  • The USB 3.0 cable has 9 internal conductors vs. 4 in USB 2.0.

    Four of the nine match the USB 2.0 configuration (two are for power and two are for signal). Connecting a USB 3.0 device with a USB 2.0 cable uses those conductors and operates like a USB 2.0 device.

    The other five are signal conductors, which are used for the communication method that provides USB 3.0 "superspeed" (a good general description can be found here).

  • USB 3.0 cables have a limit of 3 meters vs. the USB 2.0 limit of 5 meters.

    (Note that this is a practical limit. The cable can be any length as long as it meets all of the electrical requirements in the specification. The 3 meter limit is based on maximum allowable losses using the largest recommended wire size so that the cable is flexible.) source: specs

Related to power:

  • A USB 2.0 cable may not be adequate for a high current USB 3.0 device.

    Some USB 3.0 devices draw more power than USB 2.0 devices. The power conductors in USB 3.0 cables need to be able to carry 900mA instead of 500mA for USB 2.0.

Additional information on USB 3.0 vs. 2.0 can be found here.

fixer1234

Posted 2015-07-07T15:14:54.043

Reputation: 24 254

1yep, it works with legacy USB speeds using legacy cords. – Francisco Tapia – 2015-07-07T15:42:44.923

What about UTP? http://superuser.com/questions/937437/making-usb-extension-cables-using-utp-cable?noredirect=1#comment1273499_937437

– arielnmz – 2015-07-07T16:05:50.293

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@arielnmz: To achieve USB 3 speeds, the specs define the performance characteristics the wire needs to meet. I'm not familiar with whether UTP could meet the requirements, but the spec is here: http://www.intel.com/content/dam/doc/technical-specification/usb3-internal-connector-cable-specification.pdf

– fixer1234 – 2015-07-07T16:13:18.800

4And note the reverse on power: I have a USB2 device that draws too much power, it originally had a two-headed cable that let it draw power from two ports at once. Now it's fed from a single USB3 port with no gripes about drawing too much. – Loren Pechtel – 2015-07-07T21:31:53.980

+1 extra pins/cores are required in USB3 to reach the higher rate. – Not loved – 2015-07-09T22:45:39.607

Just a quick question, what about if I have a usb 2.0 harddrive with Y-cable, can I replace with USB 3.0 cable for a better current? – Bilo – 2015-07-10T17:22:49.297

2@Bilo: If you plug it into a USB 3 port it should work (a USB 2 port limits the current output to 500mA). But that's a waste of a USB 3 port. You would be better off getting a USB 3 enclosure for the drive and taking advantage of 10x the speed. – fixer1234 – 2015-07-11T03:44:21.047

@fixer1234 unless it's an SSD you wont get anywhere near 10x the speed, even a really good spinning disk is going to top out somewhere around the 100MB/s mark. If it's a cheap or old drive it might well not even saturate USB2. – Joseph Rogers – 2018-10-03T10:13:37.787

1@JosephRogers, you're right. The USB port will be a bottleneck as long as it's slower than the peak transfer rate. You don't need to saturate it; performance will be degraded if the peaks exceed the bandwidth. On a good hard drive, that can be several times the USB 2.0 limit. With a good drive, you can benefit from USB 3.0's 10X speed, but you won't realize 10x the transfer rate. That was poor wording in my comment. – fixer1234 – 2018-10-03T16:32:41.003

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USB 3.0 jacks will work with older USB 2.0 cords, but at USB 2.0 speeds. The newer USB 3.0 connectors have more wires to carry the higher data rate.

DrMoishe Pippik

Posted 2015-07-07T15:14:54.043

Reputation: 13 291

2Is it the same with USB 1 cables? Will USB 1 cords work in a USB 3 jack at USB 1 speeds; or will they not work at all? – user56reinstatemonica8 – 2015-07-07T15:50:10.137

1@user568458 - USB 2.0 is backwards compatible with USB 1.0 and USB 1.X cables and devices. Since USB 3.0 devices plugged into a USB 2.0 port will act like a USB 2.0 device this means a USB 3.0 device when plugged into a USB 1.0 or 1.x port will act like a USB 1.0 or 1.x device. – Ramhound – 2015-07-07T16:26:39.293

3@user568458 All USB cables were identical before USB 3.0. – gronostaj – 2015-07-10T08:58:35.010

Asked: 2015-07-07T15:14:54.043

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