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Using USB-C and Thunderbolt Cables and Ports on MacBook

The latest MacBook Pro sheds almost all ports; it includes only a headphone jack and a few USB-C connectors, and it also supports the latest high-speed Thunderbolt 3 standards. What’s the difference?

Despite the “U” in USB standing for “universal,” the standard has come under fire for confusing consumers. Some cable manufacturers have been accused of breaking norms, and cheap USB-C cables might damage your electronics. Let’s try and make sense of this mess of MacBook ports.

What is USB-C?

Also known as USB Type-C, USB-C is a symmetrical connector designed to replace the existing Type-A and Type-B connectors. Unlike its predecessors, you can insert USB-C in any way. It also means that you no longer need to be confused about whether you’re holding the cable correctly.

USB-C strictly relates to the shape of the connector and the port into which it fits. It’s not a standard for data transmission, like USB 2.0 or 3.1. Despite USB-C using a 24-pin connector, many different standards have used the USB-C shape.

All USB-C cables must carry at least a 3A current up to 60W at 20V. Many smartphones use the USB-C standard to facilitate fast charging, which pulls in a higher voltage thanks to the increased power throughput.

Some USB-C cables can carry 5A for 100W at 20V, enough to charge the latest high-end MacBooks and HP Spectre line of laptops (to name a few). Devices using the USB-C standard for data and power transfer include Google’s Pixel smartphones, the latest MacBook Pro, the Nintendo Switch, and many portable USB batteries.

What Is Thunderbolt 3?

Thunderbolt is a hardware interface developed by Intel and Apple and introduced to the market in 2011. Thunderbolt 3 is the latest iteration of this standard, which has become a signature MacBook port. Whereas the first two generations of Thunderbolt devices used the Mini DisplayPort connector, Thunderbolt 3 uses USB-C exclusively.

Much of the confusion surrounding USB-C and Thunderbolt relates to the shape of the connector. You cannot buy Thunderbolt 3 cables that don’t use the USB-C standard. At the same time, Thunderbolt 2 lines don’t fit into Thunderbolt 3 ports since they’re a different shape (they are backwards-compatible with the correct adapter, though).

mini displayport and thunderbolt 1/2 connector

Thunderbolt 3 improves on the standard in almost every way. It doubles the bandwidth of the previous generation to 40Gbps. It’s also USB compatible, which means it can combine multiple technologies into one port. Add to this the array of Alternate Mode applications outlined above, and you’ve got one port to rule them all.

The latest standard supports HDMI 2.0, DisplayPort 1.2 (with resolutions up to 4K), and PCIe 3.0. This provides enough bandwidth to realise the potential of external graphics cards finally. It can also incorporate USB Power Delivery, with up to 100w of power throughput. This is how Apple was able to replace MagSafe power connectors with USB-C ports on its latest machines.

usb-c and thunderbolt 3 connectors

Thunderbolt has one last trick up its sleeve: daisy-chaining. You can connect Thunderbolt devices in a daisy chain, allowing you to link multiple devices together and still only use a single USB port on your computer.

The superior speeds and connectivity over USB 3.1 and similar standards are made possible because Thunderbolt cables are active. A microchip built into the connector enables higher performance and greater versatility than standard “passive” USB cables. You can still use passive USB-C cables used to connect some Thunderbolt 3 devices, but they will work at much slower speeds.

Compatibility With MacBook and Other Macs

The following Apple computers are compatible with Thunderbolt 3, using USB-C connectors:

  • MacBook Pro, late 2016 and newer
  • iMac, mid-2017 and newer
  • iMac with Retina Display, mid-2017 and newer
  • iMac Pro, late 2017 and newer
macbook ports - macbook pro connectors

The following Apple computers are compatible with Thunderbolt 2, using Mini DisplayPort connectors:

  • MacBook Pro Retina, late 2013-mid 2015
  • MacBook Air, early 2015-mid 2017
  • iMac, late 2015
  • iMac with Retina Display, late 2014-late 2015
  • Mac mini, late 2014
macbook ports - macbook air right side

The following Apple computers are compatible with the original Thunderbolt standard, using Mini DisplayPort connectors:

  • MacBook Pro Retina, mid-2012-early 2013
  • MacBook Air, mid-2011-early 2014
  • iMac, late 2012-mid 2014
  • Mac mini, mid 2011-late 2012

Not sure which computer you have? Boot it up, log in, and click on the Apple menu in the top-left of the screen. Select About This Mac, and you’ll see information pertaining to your model beneath your current macOS version number. Note that the regular MacBook model doesn’t support Thunderbolt at all, just USB-C and USB 3.1.

Thunderbolt 3 Cables and Adapters

Apple does not supply a Thunderbolt 3 cable with new MacBooks. The USB-C cables and adapters used to charge Apple’s latest laptops are only capable of USB 2.0 speeds. Depending on the model, these can carry power throughputs of 27W, 60W, and 87W at maximum load.

usb-c charging cable

Buying the right cable is important. If you’re buying a cable to use with your new USB-C Mac, you have two choices: USB or Thunderbolt.

In terms of speed:

  • USB 3.1 gen 1 (also known as SuperSpeed USB 3.0) supports up to 5Gbps
  • USB 3.1 gen 2 supports up to 10Gbps
  • Thunderbolt 1 up to 10Gbps
  • Thunderbolt 2 up to 20Gbps
  • Thunderbolt 3 up to 40Gbps

USB-C cables come in a variety of speeds and configurations. The thicker (5A) cables will carry a higher voltage and allow you to charge more power-hungry devices. USB is fully backwards compatible, and you can even use USB-C with the traditional USB-A connector if you buy an adapter.

USB-C cables will have some limited Thunderbolt compatibility, and transfer speeds may even exceed those of USB 3.1. However, because USB-C cables are passive and not active, they are no replacement for Thunderbolt 3 cables.

Thunderbolt 3 cables are generally more expensive since they have more technology. They aren’t always compatible with the USB 3.1 gen two standards, especially if they’re longer than around 1.5 feet.

Thunderbolt 3 or Not: What’s Best for My Needs?

If you’re confused, you’re not alone. The industry has done little to ease the head-scratching that comes with deciphering which peripheral you need. If in doubt, consider what you will use your cable for. Here are some ideas:

apple thunderbolt 3 cable

Then there’s the minor issue of adapters. Some early Thunderbolt 3-compliant accessories, like Ethernet or HDMI port adapters, are not supported by the latest MacBook Pro. macOS will block some peripherals if they are not explicitly endorsed.

If you’re buying an adapter specifically for your Mac, it’s worth going to ensure it’s compatible with macOS. That means buying Apple’s first-party products, buying your peripherals from an Apple Store, or searching the web and asking around before you buy.

Wired vs. Wireless: The Future of MacBook Ports

Cables can ruin the sweetest of setups. The confusion between USB-C, USB 3.1, poorly-named iterations, and Thunderbolt 3 doesn’t help. But they’re here to stay for the foreseeable future, and we’ll have to live with it. On the plus side, many once-wired peripherals and gadgets are now totally wireless. The latest smartphones can charge wirelessly, wireless keyboards and mice are the norms, and a new Wi-Fi standard is introduced every few years, pushing network speeds ever higher.

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