1、Physical Differences
1) Color
USB 3.0 Connectors are different from USB 2.0 Connectors and the 3.0 connectors are usually colored blue on the inside in order to distinguish them from the 2.0 connectors.
2) Metal contact
USB 3.0 is characterized with 9pin metal contact, which classifies it from USB 2.0 who featured with 4pin metal contact. The 4pin metal contact in the front part of USB 3.0 cable is the same as that of USB 2.0, but the 5pin in the back part is exclusive.
3) Backward Compatible
USB 3.0 is compatible with USB 2.0. However, the USB 3.0 product will perform at the same level as a USB 2.0 product, so speed and power benefits will not be fully realized.
USB 3.0 receptacles are electrically compatible with USB Standard 2.0 device plugs if they physically match. USB 3.0 type-A plugs and receptacles are completely backward compatible, and USB 3.0 type-B receptacles will accept USB 2.0 and earlier plugs. However, USB 3.0 type-B plugs will not fit into USB 2.0 and earlier receptacles.
This means that USB 3.0 cables cannot be used with USB 2.0 and USB 1.1 peripherals, although USB 2.0 cables can be used with USB 3.0 devices, if at USB 2.0 speeds.
4) B-type port
Because of the 5pin metal contact, standard USB 3.0 B type port is bigger than that of USB 2.0.
5) Identification
USB 3.0 port is identified with the symbol shown in the above picture. Its double “S” means “Super Speed”.
Additionally, USB 3.0 cable is thicker than that of USB 2.0 because of its increased routes.
2、Transmission Rate
This year, USB 3.0 hard drives and other gadgets are finally hitting stores. They cost a little bit more up front, but the marketing speak promises data transfer speeds 10 times faster than the old USB 2.0 standard that you’ve been using for the past 10 years.
USB 3.0 is capable of transfer speeds of up to 5Gbps (gigabits per second); that’s a little over 10 times faster than USB 2.0′s 480Mbps (1,000Mbps equals 1Gbps). In practice, it won’t always be this much faster — mileage may vary depending on hardware configuration — but it will always be much faster than USB 2.0
USB 2 had a maximum speed of 480 Mbps, which was great at that time but now it might not be enough because we now have USB thumb drives that are 64 GB in size, cell phone and PDAs that have a lot of internal storage built in, and even at 480 Mbps a full transfer of data in between devices can take a long time. In comparison to this, USB 3.0 boasts a maximum transfer speed of 4.8 Gbps yes, 4.8 Gigabits per second, and almost 10 times faster than USB 2.0. Even with realistic numbers you can transfer data between your computers to a 64 Gigabyte thumb drive to full capacity in under 20 minutes!
The New York Times decided to test this “10 times faster” line, so it used brand new USB 3.0 hard drives and a desktop computer with an ideal configuration for transferring data over a USB 3.0 cable. In the test, writer Rik Fairlie copied a folder containing 10GB of files. He did this once over USB 2.0 and once over USB 3.0. The USB 3.0 connection took 6 minutes, 31 seconds, and the USB 2.0 connection took 22 minutes, 14 seconds. That’s still a dramatic improvement (USB 3.0 was about 3.5 times faster), but it doesn’t live up to the marketing hype.
Faster speed is not the only difference, power usage and requirements for USB 3 devices are much “greener”. The USB 3 devices will provide more power when needed to the device to achieve a maximum throughput and conserve power when the device is connected but is idling. Modern operating systems such as Windows 7 already has support built in for USB 3.0 and Mother Board manufacturers already have the USB 3 port built in on the upcoming motherboards.
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