Why don’t external hard drives without power cords have a higher rotation speed?

June 30, 2010 in external hard drives | Comments (5)

Almost all external hard drives without power cords have a rotation speed of 5400 RPM or less. And the rare external hard drives without power cords that have a 7200 RPM have a ridiculously tiny amount of storage.

Also, why don’t hard drives without power cords go above 200GB? What exactly is the power constraint?

The reason they don;t spin faster is because the USB interface can only provide so much power. trying to spin it to 7200 RPM would draw too much juice!

The capacity is due to the same thing. There are silver discs inside a harddrive called platters. The more storage in a drive, the more and larger platters there are. 200GB is probably the optimum storage to wieght (of the platters) ratio they cold find that would still stay under the power limits of the USB interface.

5 Responses to “Why don’t external hard drives without power cords have a higher rotation speed?”

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  1. Comment by Jason S — June 30, 2010 at 9:58 pm  

    The reason they don;t spin faster is because the USB interface can only provide so much power. trying to spin it to 7200 RPM would draw too much juice!

    The capacity is due to the same thing. There are silver discs inside a harddrive called platters. The more storage in a drive, the more and larger platters there are. 200GB is probably the optimum storage to wieght (of the platters) ratio they cold find that would still stay under the power limits of the USB interface.
    References :

  2. Comment by s j — June 30, 2010 at 10:29 pm  

    USB 2.0 only has 5 volts and low amps so it can’t handle the power draw of bigger faster hard drives.
    References :

  3. Comment by PoohBearPenguin — June 30, 2010 at 11:19 pm  

    Those external drives are the ones that are used in laptops. They don’t need as much power, so they can be run off the USB connection. However, this also means they spin slower and aren’t as large (capacity-wise) as regular desktop drives.

    Don’t worry, though, these drives are still plenty faster than your USB 2.0 port.
    References :

  4. Comment by StuArtNJ — June 30, 2010 at 11:35 pm  

    They are USB bus powered drives that are typically suited for laptops- laptops that power your drive would go dead faster with a drive higher than 5400 RPM.

    The small portable drives that are USB powered almost always have a notebook drive installed in the case for power consumption management for your battery powered laptop.
    References :

  5. Comment by zubairwaqas — June 30, 2010 at 11:43 pm  

    First of all haven’t u heard about usb2 technology, usb1 technology was built just for flash drives, Keybords,etc. the new USB2 technology will make the new external drive run faster.

    there 500 GB out there but to expensive. got the idea
    References :

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