How can I tell if my hard drive enclosure can power my hard drive?

Hard drive enclosures require power from your system's USB port. Although you can plug in any standard SATA drive, USB ports only supply a limited amount of power and are not able to power all of the hard drives plugged into the system. The power capabilities of the USB port combined with the power requirements of the attached hard drive will determine if the hard drive enclosure will work in your setup. The power (in mA) supplied by the USB port must be greater than the requirements of the hard drive. A USB 2.0 port can supply a maximum of 500 mA (0.5 A), and a USB 3.0 port can supply a maximum of 900 mA (0.9 A). You can usually find the power requirements of your hard drive in the technical specifications on the label of the hard drive or on the manufacturer's website.