While USB 4 is the latest and fastest generation, the most common USB ports on PCs and peripherals have a 3 in the version number, specifically USB 3.2 or USB 3.1, or even 3.0. When looking at spec sheets, note that there are generation numbers after the USB 3.2 or 3.1. For example, USB 3.2 Gen 1, USB 3.2 Gen 2, and also USB 3.2 Gen 2x2. And yet some ports with different version numbers actually have the same speed. Table 2-1 shows different USB 3 versions and speeds.

The 20 Gbps speed is named USB 3.2 Gen 2x2, because it uses two 10 Gbps lanes to give the 20 Gbps speed. There is also a lesser-used version called USB 3.2 Gen 1x2, which is 10 Gbps and nearly identical to USB 3.2 Gen 2. The difference is that, while USB 3.2 Gen 2 has a single, 10 Gbps data lane, USB 3.2 Gen 1x2 uses two 5 Gbps lanes to get to the 10 Gbps total.

Both the 5 Gbps and 10 Gbps speeds are available with either USB Type-A or USB Type-C connectors. USB Type-A ports have the traditional, rectangular connectors that can only be inserted one way. USB Type-C ports are smaller, oval-shaped and reversible.

However, if using USB 3.2 Gen 2x2 (20 Gbps), then the USB Type-C is being used. The Type-A ports cap out at 10 Gbps. Also, though rare, the USB 3.2 Gen 1x2 (also 10 Gbps) can only use USB Type-C.

When using a USB 3.2 Gen 2 port, and need to take advantage of the 10 Gbps speed, use a cable that supports 10 Gbps and a peripheral that does the same. If need to get 20 Gbps speeds, all three pieces: the port, the peripheral, and the cable, must support that speed.