Do you need to plug in the power cable for all USB 3 devices? what is the point of the power cable?

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Accepted Answer

I'm using this card with a Western Digital mypassport usb 3 drive and the power cable is required for the drive to spin up.  You basically plug one end of the power cable into an existing usb port on your device and the other end into the card.  if you don't have a usb port on the same side as your card slot the supplied cable will probably not be long enough, FYI.

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