In the USB 3.1 specification, cables were designed to use a single lane of either 5Gbps or 10Gbps for data transfer. The update to USB 3.2 unlocks a second lane, which effectively doubles the capacity. With SuperSpeed-certified cables and a USB 3.2 host (meaning the thing you’re plugging into), you can push 2GB across the connection each second. These are Thunderbolt 2 numbers, but USB is available on many more devices.
As USB specifications have advanced, one thing has become evident: Not all cables are created equal. There was much more margin for error prior to USB Type-C. But now, using the wrong hardware can prevent a cable from reaching the specified data rates, or transferring the correct amount of power. Some Type-C cables with poor internal design can even cause damage to your devices after being connected. The USB-IF recognized this, so it started a certification program a while back. If you have a USB Type-C cable certified for 10Gbps “SuperSpeed,” you’re already well on your way to unlocking the new speeds.
Existing Type-C SuperSpeed cables were designed with support for that second data lane so that they will work with USB 3.2 (look for the SuperSpeed logo below). Even cables that are only certified for 5Gbps will still get a second data lane for double the speed. What might be harder is finding a USB 3.2 host device. None of those exist yet, but the port will be the same Type-C we’ve come to know over the last few years.
Even with a proper USB 3.2 host, you might not see blazing fast 20Gbps transfers. The storage technology on the other end of that cable might not be fast enough. For example, the latest UFS 2.1 flash storage in phones has a maximum data rate of 1.2Gbps. Some USB-connected SSD drives can saturate a USB 3.1 cable, so there may be some benefit for USB 3.2 there. This move is more of a future-proofing move.
There won’t be any certified USB 3.2 host devices until later this year or early next. That’s when the USB-IF expects to have the standard complete.