The USB Implementers Forum (led by Intel) released the USB 3.0 spec to hardware partners last week after some reported disputes with AMD and Nvidia.

Features
* USB 3.0 will be backwards-compatible with USB 2.0
Like the upgrade from USB 1.1 to 2.0, the new 3.0 connectors and cables will be physically and functionally compatible with hardware from the older specs. Of course, you won’t be able to maximize your bandwidth unless you’re using a USB 3.0 cable with Superspeed devices and ports, but at least plugging a 3.0 cable into a 2.0 port won’t blow up your PC.

* The maximum speed of USB 3.0 is 4.8Gbps
USB 3.0 SuperSpeed will be 10 times faster than the 480Mbps limit of the 2.0 spec. The example Intel likes to give out when talking about the new speed is that transferring a 27GB HD movie to your future media player will only take 70 seconds with USB 3.0

* Uploads and downloads are kept on separate data lanes
With USB 3.0, two new lanes will be dedicated to transmit data, while another pair will handle receiving data. This not only accounts for the significant speed boost, but also allows USB 3.0 to both read and write at the same time from your portable storage device.

* USB 3.0 will charge more devices, quicker
Not only will USB 3.0 cables facilitate faster transfer speeds, but they’ll carry more power, too. The USB-IF recognizes the growing number of portable devices that charge via USB (cellphones, MP3 players, digital cameras), and have bumped the power output from about 100miliamps to 900 milliamps. That means not only will you be able to power more than 4 devices from a single hub, but the increase current will let you charge up heftier hardware as well.

* USB 3.0 will be more power efficient
One of the mandates of the new spec is more efficient power-usage protocols. USB 3.0 abandons device polling in favor of a new interrupt-driven protocol, which means non-active or idle devices (which aren’t being charged by the USB port) won’t have their power drained by the host controller as it looks for active data traffic. Instead, the devices will send the host a signal to begin data transfer.

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