Thunderbolt 3 Cable, Port and Power Performance Expectations
CablesIt is important to understand the effects of Thunderbolt 3 cables used between Thunderbolt 3 ports for both power capability and data rates. Consider whether the connection is Host to Device (i.e. PC to Monitor), Host to Host (i.e. 20Gbps Thunderbolt Networking), or Device to Device (i.e. 40Gbps Daisy Chaining). Popular Thunderbolt 3 cables designs arranged in increasing relative price include:
- 0.5m Passive 40Gbps, 5A (typically $30 SRP)
- 1m Passive 20Gbps, 5A
- 2m Passive 20Gbps 3A
- 1m Active 40Gps, 5A
- 2m Active 40Gps, 5A (typically $80 SRP)
PortsAlso, Thunderbolt 3 ports can be configured with 2 or 4 PCIe lane designs. Systems with the 2-lane designs will only support up to 20 Gbps data transfers. Systems with 4-lane designs will support up to 40 Gbps. An example of this is the new MacBook Pro 13-Inch Model. Per Apple, "MacBook Pro models introduced in 2016 vary slightly in the data speeds they provide to each Thunderbolt 3 port."
- MacBook Pro (15-inch, 2016) delivers full Thunderbolt 3 performance on all four ports.
- MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports) supports Thunderbolt 3 at full performance using the two left-hand ports. The two right-hand ports deliver Thunderbolt 3 functionality, but have reduced PCI Express bandwidth. Always plug higher-performance devices into the left-hand ports on MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports) for maximum data throughput.
- MacBook Pro (13-inch, 2016, Two Thunderbolt 3 Ports) delivers full Thunderbolt 3 performance on both ports.