Usb controller drivers need updating
This gives USB 3.0 a potential total bandwidth, if used both ways, of twenty times that of USB 2.0.
Front view of a Standard-A USB 3.0 connector, showing its front row of four pins for the USB 1.x/2.0 backward compatibility, and a second row of five pins for the new USB 3.0 connectivity.
The use of unicast and the limited amount of multicast packets, combined with asynchronous notifications, enables links that are not actively passing packets to be put into reduced power states, which allows better power management.
The "Super Speed" bus provides for a transfer mode at a nominal rate of 5.0 Gbit/s, in addition to the three existing transfer modes.
Earlier USB concepts such as endpoints and the four transfer types (bulk, control, isochronous and interrupt) are preserved but the protocol and electrical interface are different.
The structural topology is the same, consisting of a tiered star topology with a root hub at level 0 and hubs at lower levels to provide bus connectivity to devices.
The Super Speed transaction is initiated by the host making a request followed by a response from the device.
Accounting for the encoding overhead, the raw data throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (0.4 GB/s or 400 MB/s) or more in practice.
All data is sent as a stream of eight-bit (one-byte) segments that are scrambled and converted into 10-bit symbols via 8b/10b encoding; this helps the receiver to decode correctly even in the presence of electromagnetic interference (EMI).
The available current for low-power (one unit load) Super Speed devices is 150 m A, an increase from the 100 m A defined in USB 2.0.