External HD's and bus power?

Discussion in 'Mac Accessories' started by Tobias Funke, Jul 21, 2013.

  1. Tobias Funke macrumors 6502a

    Tobias Funke

    Apr 3, 2012
    Are there any plus or minus points to using bus powered external HD's compared to using external HD's with there own power supply ??

    They will be 3.5 inch HD's and used on the apple thunderbolt display.

    Thank you.
  2. simsaladimbamba

    Nov 28, 2010
  3. Tobias Funke thread starter macrumors 6502a

    Tobias Funke

    Apr 3, 2012
    Looks like Amazon reviews for same brand 2.5 inch and 3.5 inch HD's are all bunched together!!!!!

    Thanks for the reply.
  4. opinio macrumors 65816

    Mar 23, 2013
    Bus powered are 2.5" while ac powered are 3.5". Although you can also power a 2.5".

    2.5s are mostly 5400rpm and are obviously smaller in capacity. Unless you get a quality 7200rpm drive like a Scorpio black or HGST 7200rpm drive it is likely your 2.5" is slow no matter wether it is usb3.0 or t-bolt etc.

    3.5s are more readily available in 7200rpm and are lot cheaper for their capacity. Although there are still a lot of 5400rpm 3.5" drives. A seagate 3tb is always 7200rpm and is exceptionally fast for a budget HDD.

    In short, 2.5s are more costly for capacity and are usually slower on average. 3.5s are far better value for capacity and come as large a 4tb in a single drive. They are usually faster but mainly because there are more 7200rpm drives around in 3.5".

    There are exceptions to the above in that you can get 10,000 rpm HDDs like the velociraptor and you can also obviously get 2.5" SSDs. They are not available in a standard USB enclosure though unless you buy premium configs or build your own.
  5. Giuly macrumors 68040


    If you have a laptop and want to take it with you, get a bus-powered 2.5" hard drive - or SSD.

    If it's just attached stationary to you Thunderbolt Display, or you need storage >2TB which is what I assume when you talk plural, get 3.5" hard drives. They offer more TB per $. And yes, make that 7200RPM drives while you're at it.

    There are your plus and minus points, sort of.

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