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Thread: Power Supply + Watts Ratings

  1. #1
    Bronze Member Island_Boy_77's Avatar
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    Question Power Supply + Watts Ratings

    Hi all

    This is a 2-part question. Firstly, if I want to work out the proper wattage rating on a PSU, is this the correct formula:
    Amps x Volts = Watts?
    The PSU I want to check lists the following:
    +3.3V 18A
    +5V 30A
    +12V 19A
    -5V 0.5A
    -12V 0.8A
    +5VSB 2A
    If the formula of A x V = W is correct, then I calculate that the rating on the PSU should be 460W.
    3.3 x 18 = 59.4
    5 x 30 = 150
    12 x 19 = 228
    5 x 0.5 = 2.5
    12 x 0.8 = 9.6
    5 x 2 = 10

    Secondly, is there a tool available, either hardware or software, that can measure the total Watt loading of a system while it's running? Further, is there a website that gives a good guide to the approximate Watt ratings of major internal components - a Wattage Calculator, if you like?

    Many thanks.

  2. #2
    Head Honcho Administrator Reverend's Avatar
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    Try these:

    Hardware - Kill A Watt

    Software - Speedfan

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  3. #3
    Bronze Member Island_Boy_77's Avatar
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    Thanks for those links. Are my calculations for the wattage on the PSU correct? Also, is there a website where one can figure out the wattage of components prior to a system build?

  4. #4
    Head Honcho Administrator Reverend's Avatar
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    Quote Originally Posted by Island_Boy_77 View Post
    Also, is there a website where one can figure out the wattage of components prior to a system build?
    The manufacturers website should have links to the specs.

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  5. #5
    Security Intelligence TZ Veteran cash_site's Avatar
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    Unsure if you've continued your research NZ, but i think you are correct for the power formula and the practice of PSU to sum up all their rails. This makes the need to carefully double check AMPS! 500W from one company is not the same as 500W from a better company

    Finally, yeah, check with your hardware supplier for Max Wattage... i.e. Quads usually run ~100W, Video can use ~500W!!! HDD et al ~100W ... hence the need for min 500-650W these days....

    I use a device that plugs inline with my pc and wall, it gives real time WATT usage. Mine uses 100W idling and upto 400W on full load etc.

    --- 0wN3D by 3gG ---

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