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I'm on the verge of buying myself a new bus-powered USB 3.0 2.5-inch external hard drive. However, my computer only has USB 2.0 ports on it. I understand that the USB 3.0 HDD will simply run slower on USB 2.0 until I upgrade my machine, but my question is this:

Can I be sure that my USB 2.0 port can provide enough power for this bus-powered USB 3.0 device?

I read that the maximum power provided by USB 3.0 is 900 mA, which is almost twice the maximum power provided by USB 2.0: 500 mA. This made me think that even though USB 3.0 is backward compatible with USB 2.0, a USB 3.0 powered device may not work on a USB 2.0 port. If it depends on the device, what would indicate USB 2.0 power compatibility when choosing which external hard drive to buy?

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1 Answer 1

My personal experience with a 2.5-inch Toshiba Cavino 1TB drive and it works fine in a USB 2 slot. It only has a single USB cable.

The only difference is when it is plugged into a USB 2 port, the activity light is white while in USB 3 port the activity light is blue.

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