Why USB 3.0 Is So Much Faster
The key to the breakneck speed of USB 3.0 is the vastly improved drivers, which are not "polling-type" mechanisms, O'Neill said. "In a polling-type driver [which USB 1.0 and 2.0 use], every transmission had to be initiated and acknowledged by the CPU," O'Neill said. "Basically, in USB 1.0 and 2.0, the CPU was involved in handling every packet of data that was transferred [in the stream]. So just rewriting the protocol so that the CPU initiates the transaction but doesn't need to acknowledge every single packet-it only does it at the beginning and at the end.""In an enterprise, for example, let's say you connect a PC to a USB hub with five ports, and then you connect a bunch of devices to it. Unless all those devices are asleep, the hub has to send a poll to every one of the client devices," O'Neill said. "It's been a dirty little secret that USB claims to have effective power management, but in reality if you have more than one peripheral connected, the whole thing is broken. USB 3.0 has addressed that, so that each device is viewed independently from the host perspective," O'Neill said. "So you can't effectively have all but one of the devices connected powered down and basically ... not 'woken up' to poll for data. Overall, power management is going to be a huge benefit for the end consumer."
Additionally, USB 3.0 features much-improved power management, O'Neill said.