What’s the difference between… USB 3.0 and 3.1?
QI’m shopping for a new PC, so I’ve been looking at adverts and trying to make sense of all the specifications. One that’s causing me no little confusion is USB. My old Vista PC has four USB 2.0 ports. Some new PCS have USB 2.0 ports, but many also have USB 3.0. I’m confident that USB 3.0 is a newer and faster version of USB 2.0 but I’ve also seen some PCS with USB 3.1 ports. I assume that USB 3.1 is in turn also better than USB 3.0, but I don’t understand how or why. What’s the difference between all these standards? Graham Hobson
AStrictly speaking, USB 2.0, 3.0 and 3.1 aren’t physical ports. Instead they are methods of transmitting data and delivering power. You’re right that each is faster than its predecessor. USB 2.0 offers theoretical speeds of up to 480Mbps, USB 3.0 up to 5Gbps (or about 10 times faster than USB 2.0), and USB 3.1 up to 10Gbps.
Any one of these can, in theory, be delivered over one of several connector shapes. The commonest by far is USB Type-a, which is the flat, rectangular plug-and-socket combination that most of us know as USB. You might also recognise Type-b because this squarer port is sometimes fitted to printers. USB 3.0 Type-a plug and sockets tend to have a blue plastic insert, but this is only a recommendation of the specification – not a requirement.
Then there’s Type-c: the newest, smallest version that also adds convenience because the connection is reversible (so you can plug it in either way up). This is now commonly referred to as USB 3.1 but, accurately, it’s a USB Type-c socket that can deliver either USB 3.0 or 3.1 speeds and more power (of up to 100 watts).
In a failed attempt at clarity, the USB Implementers Forum (USB-IF, www. usb.org) came up with ‘USB 3.1 Gen 1’ and ‘USB 3.1 Gen 2’. The former describes a USB Type-c connector that delivers only USB 3.0 speeds, while the latter signifies Type-c able to handle USB 3.1 data transfers.