The new USB 3.0 interface uses less power and is more energy efficient. How?
USB 2.0 uses something called polling. Imagine leaving all the lights on in your house all the time in anticipation of needing to use one of the rooms. It would waste a lot of energy right?
USB 3.0 now utilises asynchronous notification which means it isn’t on all the time in anticipation of a data transfer between an external hard drive for example. Instead the external hard drive notifies the USB 3.0 host and when both are ready the data transfer takes place. It’s like the person entering a room only turning on the light when needed.
Increased speed and efficiency
The computers bus (the computers data transfer highways) encounters less traffic because of the speed of data transfers in USB 3.0. This means the bus powers down a lot quicker.
Link power is better managed
The link between the USB 3.0 card and the device plugged into it do not constantly need to be active because polling has been eliminated. The idle state of the link and the longer it stays idle causes the computers bus to better manage power resulting in power savings.
Huge power savings
All these factors combined mean that USB 3.0 is much less power hungry than USB 2.0. In fact the developers of USB 3.0 estimate that 25% less power is used when transferring 20 MB of data compared to USB 2.0. USB 3.0 is also backwards compatible.
External Solid State USB 3.0 drives are perfect for low power usage.