How fast are the MacBook's USB 3.0 and Thunderbolt ports?

Thunderbolt can transfer a full-length, high-definition movie in less than 30 seconds.

With the launch of the new MacBook Air and MacBook Pro this week, Apple became the only laptop manufacturer to offer both a high-speed Thunderbolt port and two USB 3.0 (SuperSpeed USB) ports for external peripherals.

By upgrading from the USB 2.0 standard to 3.0, the laptops offer 10 times the I/O bandwidth for external devices. That translates into markedly faster backups to external storage devices.

The Thunderbolt protocol offers even greater performance. On paper, Thunderbolt offers a 10Gbps transfer rate, compared with SuperSpeed USB's 5Gbps. Thunderbolt is 12 times faster than FireWire 800 and up to 20 times faster than USB 2.0.

Thunderbolt can transfer a full-length, high-definition movie in less than 30 seconds. SuperSpeed USB would take about 70 seconds to perform the same task, according to Jeff Ravencraft, president of the USB Implementers Forum (USB-IF).

Based on copper, the Thunderbolt specification contains two protocols: PCI Express (PCIe) and DisplayPort. The Thunderbolt chip switches between the two protocols to support varying devices. DisplayPort offers HD display support as well as eight channels of HD audio. A Thunderbolt connector has two full-duplex channels; each are bi-directional and capable of 10Gbps of throughput.

Thunderbolt also offers up to 10 watts of power to a device. SuperSpeed USB is optimized for power efficiency. It uses only 1.5 amps of power for charging devices, or about one-third of the power of its predecessor Hi-Speed USB (2.0).

Thunderbolt has the ability to serve as a transport for PCI Express (PCIe), something USB is incapable of. PCIe is a computer expansion bus standard, the main advantage being that users who've already invested in PCIe-enabled devices can continue to use them.

One major drawback to Thunderbolt is the high cost of hardware because it is still a fairly new technology. For example, a SuperSpeed USB cable sells for around $3. A Hi-Speed USB (2.0) cable sells for about $1.50, and the chipset sells for less than $1, according to USB-IF Chief Technology Officer Rahman Ismail.

In contrast, a Thunderbolt cable sells for $49. Intel just began shipping a lower-cost chipset, dubbed Cactus Ridge.

By the numbers

SuperSpeed USB 3.0 Thunderbolt
Speed 4.8Gbps 10Gbps
Power for devices 4.5 watts 10 watts
Cost $4.49 (for 2-meter cable) $49.00 (for 2-meter cable)
Connector size 11.5mm X 4.5mm 8.3mm X 5.4mm
Downloading 25GB HD movie 60-75 seconds 30 seconds
Source: Intel, USB-IF

USB is among the most successful interfaces in the history of personal computers. Among PC and peripheral device manufacturers, USB adoption is virtually 100%. The USB installed base is more than 10 billion units, and those devices are growing at more than 3 billion a year. It's hard to imagine any external device interconnect technology that could challenge USB.

Jeff Cable, an official photographer for the USA Water Polo Team, who has covered three Olympics games, said the MacBook Pro's upgraded ports and retina display will make it the perfect machine for him.

"Not only with the processing power, the SSD, the amazing screen, but with the addition of USB 3.0 for fast downloading (using the Lexar Pro USB 3.0 reader) and two Thunderbolt ports for connecting [external storage]," he said. "I can't ask for a better tool."

Cable said having an internal SSD, as the MacBook Air and MacBook Pro now offer, is great for the speed, but it also highlights the need for a high-capacity, high-speed external device. "Shooting more than 100GB a day, a 512GB SSD won't last long," he said.

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