USB 3 (also known as "SuperSpeed USB") is the latest USB standard which offers significant performance improvements over USB 2 ("Hi-Speed USB").
What transfer rates are offered with USB 3?
- USB 3 can transfer data up to 5 Gbps.
- USB 2 can transfer data up to 480 Mbps.
- USB 1.1 can transfer data up to 12 Mbps.
Yes, USB 3 devices can use up to 900mA of power (compared to 500mA used by USB 2 devices). You'll need to use a USB 3 cable to use the 900mA of power available. USB 2 cables don't support 900mA.
Some USB computer ports have a blue insert. Why don't I see blue inserts on my Mac's USB ports?
Some manufacturers use a blue insert to designate a USB 3 port or device. All USB ports on Macs that supports USB 3 are USB 3 capable and do not have blue inserts.
What USB 3 devices are supported?
All devices that conform to what is commonly referred to as the "2008 version 1 USB 3.0 specification" are supported.
Are USB 3 hubs supported?
Hubs that conform to what is commonly referred to as the "2008 version 1 USB 3.0 specification" are supported.
How do I get the best performance from the USB 3 ports?
The first device you plug in will configure the port, so always connect USB 3 capable hubs or devices first.
What happens if I plug in a USB 2 device into the USB 3 port first?
If you plug in a USB 2 hub first, all devices connected or "daisy-chained" to that hub will operate up to the maximum transfer rate of USB 2 speed (480 Mbps).
Is USB 3 supported in Windows 7 using Boot Camp?
Yes. To implement SuperSpeed USB support on Windows 7 using Boot Camp, download and install the Windows Support Software. See http://manuals.info.apple.com/en_US/boot_camp_install-setup_10.7.pdf for more information.
Are there differences between USB 3 cables and other USB cables?
Yes. USB 3 cables:
- Use more wires than other USB cables. This makes USB 3 cables a bit thicker than other USB cables.
- Have a blue insert (usually).
- Have an "SS" symbol on the computer connector.
- Use a different connector on the device end than USB 2 cables.
- Can deliver more power to an attached device (900mA).
If the device end of the cable fits into the connector on the device, yes. However, because it has fewer wires, you won't get USB 3 speed.
How can I determine if my device is connected as a USB 3 device?
Use the System Information utility.
- From the Apple () menu, choose About this Mac.
- Click More Info.
- Click System Report.
- In the Hardware section of the System Report, click USB.
I use virtualization software to run Windows on my Mac and my USB 3 devices don't appear to be operating at USB 3 data rates. What is wrong?
Some virtualization software does not yet contain support for USB 3. Contact the manufacturer of your virtualization software for more information.
USB 3 devices are not activating or not appearing on the USB 3 bus. What could be wrong?
- Sometimes unplugging and plugging the device back in can resolve the issue.
- Try plugging the device into another USB port on the computer.
- Check to see if there is a firmware update available for your device from the manufacturer.
- If it came with an AC adapter, use it.
- Try restarting your computer.
- Try a different USB 3 cable.
- Try a different USB 3 hub.
Some USB 3 devices, hard drives in particular, can generate radio frequency interference that can cause Wi-Fi and Bluetooth devices operating in the 2.4GHz band to have issues communicating with your computer. Do not place hard drives or other USB devices behind the rear of your Mac near at the hinge of your screen. The antennas for Wi-Fi and Bluetooth are located there, and USB 3 devices placed there may interfere with your wireless connections. See this white paper for more information.