Do USB 3 & Thunderbolt external Hard Drives need separate power?

Discussion in 'iMac' started by spinstorm, Jan 1, 2013.

  1. spinstorm macrumors 68000

    Sep 14, 2007
    As I said in the title - I hate having to use a separate power cable for an external HDD.

    Does USB3 and Thunderbolt need separate power?

    I'm after a cheap 2TB backup HD that doesn't need separate power.
  2. WilliamG macrumors G3

    Mar 29, 2008
    If you buy something like the Western Digital MyBook 2TB 2.5" USB 3.0 drive, then no you don't need power. Very few, if any, laptop drives need power connected via Thunderbolt or USB 3.0.

    I've been using that above 2TB drive with no problems, and also two Thunderbolt SSDs. No power cables.
  3. Arman macrumors regular

    Aug 27, 2008
    No not if they are running SSD or laptop drives within. However, larger capacity drives which use 3.5" desktop drives will need external power.

    Example here
  4. Apple Corps macrumors 68030

    Apr 26, 2003
    Some do, some don't.

    There have been reports that some ssds running off bus power perform at less speed than if operating from a powered enclosure.
  5. COrocket macrumors 6502

    Dec 9, 2012

    Above is a portable (2.5") drive. To my knowledge 2TB is the largest portable drive available. They are found in laptops and don't require external power. on the other hand, desktop (3.5") drives needs power. That's generally the quick way to figure whether you need external power when you are shopping.
  6. garycurtis macrumors 6502

    Sep 15, 2010
    Los Angeles & Northern California
    A 500Gb Toshiba Canvio running USB 3 requires no power adaptor.

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