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    USB Hub... Adapter versus No Adapter

    Discussion in 'Accessories' started by Bryan888, Nov 9, 2007.

  1. Bryan888

    Bryan888 Notebook Consultant

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    I've noticed some USB Hubs on the market come with an AC Adapter... others don't and appear to get their power via the USB connection to the computer.

    Question is: Why do some use external power and some don't?

    What's the difference?
     
    Bryan888, Nov 9, 2007
    #1
  2. Eleison

    Eleison Thanatos Eleison

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    If the hub uses an AC adapter, it can provide power to USB devices (like cell phones that charge off USB) even when the computer is off. The AC adapter can also offset the power draw requirements of multiple devices. There's only so much power a hub can draw from a single USB port on the computer, itself, and most computers will undervolt the USB ports if power is scant, which slows down any USB 2.0 devices. An external power supply helps prevent this from happening.
     
    Eleison, Nov 9, 2007
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  3. mujtaba

    mujtaba ZzzZzz Super Moderator

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    The self-powered (adapter-less) USB hub are easier to carry, but they can supply lesser power to the connected devices. And if you use devices that consume too much power on a USB hub, they would pressure the motherboard. In that case it's advised to use powered (with adapter) USB hubs.
     
    mujtaba, Nov 9, 2007
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  4. goofball

    goofball Notebook Deity

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    It depends on what you intend to power. Powered hubs are good for devices that can draw enough power to require it, like 2.5" external hard drives or even some USB keys. Other devices that draw little power won't require that you put an adapter into a hub. Even though there may be "x" amount of usb ports on the hub, it is still limited to a max of 2.5w (500ma) of power.
     
    goofball, Nov 9, 2007
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