If someone is going to sell an $80 active Thunderbolt cable then they are not likely to go cheap and not put the little Thunderbolt icon on the connectors. Again it's far too common for USB-C cables to lack proper markings so expect inexpensive USB 2.0 cables to lack markings and expensive active cables (with the "super speed" data wires) to have the correct markings. Passive USB-C cables over a meter in length will only support USB 2.0 speeds, the "super speed" data wires will not be present in these cables. Also by being passive they will work as DisplayPort cables or any other protocol used by USB-C and does not exceed the data rate supported by the cable. Again if there are USB markings then the cable has been tested to meet the spec, the stylized "SS" icon will indicate support for 5 Gbps and there will be a small 10 or 20 on the connector if tested for the higher data rates. The cables all had to meet the same spec to comply with USB 3.0, 3.1, and 3.2, the increase in speed is from increasing efficiency in how they used the wiring in the same cables. If it has the Thunderbolt icon on the cable connectors then it's been tested to support 40 Gbps USB4 and Thunderbolt, and because the cable is passive it will work with any other protocol up to 40 Gbps.Ī passive USB-C cable that is a meter or less in length will likely support 5 Gbps USB 3.0, 10 Gbps USB 3.1, and 20 Gbps USB 3.2. A passive USB-C cable under 0.7 meters is likely to support 40 Gbps USB4 and Thunderbolt. One "rule of thumb" on USB-C cables is to simply assume they are passive unless there are some markings to indicate otherwise. It's unfortunately common for USB-C to USB-C cables to have no markings, which does not mean they will not work as Thunderbolt or USB 3.x cables but means they were not tested to meet the spec. The USB-C spec requires that the supported protocol be indicated on the cable ends with some kind of icon and/or text. Active Thunderbolt 3 cables will be longer (because the only reason to make them active is to overcome the length limit), they will be more expensive than other USB-C to USB-C cables (because there are expensive electronics in the cable), and may or may not work with USB hosts and devices (because the Thunderbolt spec only requires Thunderbolt hosts to support USB, it's optional for cables and devices). These are relatively inexpensive and because they are passive they will always work as USB cables. Passive Thunderbolt 3 cables will be no longer than about 0.7 meters. There's two kinds of USB-C to USB-C cables generally, active and passive.
There's two kinds of Thunderbolt cables, active and passive.
Can you use a Thunderbolt 3 cable to connect two Macbook 12-inch in target disk mode?