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Thread: Which Components Use Which Rails?

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    Default Which Components Use Which Rails?

    I have always been wondering which components use EXACTLY which rails. By tracing the different colored wires from my PSU I think I have the breakdown but I COULD be wrong.

    SATA: +3.3V (Orange), +12V (Yellow), +5V (Red)
    Disk Drives (DVD): +12V (Yellow), +5V (Red)
    Floppy: +5V (Red), +12V (Yellow)
    Video Card: +12V (duh)
    CPU: +12V
    Memory: +5V, +3.3V
    Fans: +5V (red) from molex, +12V from mobo????
    Sound Card: ?????
    USB devices: ?????
    Pelletier Cooler: ?????
    Water Cooling: ?????
    LED/Cold Cathode: ?????

    I have been trying to find the information all over the place but it seems I have not been able to find much. Can someone confirm this or maybe add to it?
    Last edited by SKYMTL; 01-16-2007 at 12:13 PM.

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    Default

    Fans are always +12V. But for whatever reason, the wire is red coming from the mobo.

    USB uses +5V.

    Peltiers use +12V.

    DC H2O pumps use +12V.

    LED's typically use +5V, but the transformers used for CCFL's use +12V.

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    I'm guessing the wire is red to designate positive and negative.

    Are all the other ones I listed correct?

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    Default

    USB = 5V
    PCI = 3.3V and 5V I think on the last
    Fans = 12V
    Pelt = 12V or 24V depending upon the pelt
    Water cooling (pump) either 12V or 120V AC depending upon the pump
    CCFL = 12V
    LED = 12V or 5V depending upon what rated resistor since LED's are typically < 3V (although most or all aftermarket, pre-built will use 12V)
    Memory typically is 3.3V although some motherboards use a jumper to power it via the 5V rail (DFI, MSI)
    Some fan controllers (analog) use 12V + 5V to vary the fan voltage, some (PWM) use strictly 12V and vary pulses of current to power the fan

    There's more but I'm wiped out and it's not coming to mind.

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    Is there any site where I can find the actual power consumption of things like a sound card, DVD drive, fans and cathodes?

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    Default

    Quote Originally Posted by SKYMTL View Post
    Is there any site where I can find the actual power consumption of things like a sound card, DVD drive, fans and cathodes?
    DVD Drives and fans will have it on the unit.

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    And where would I find the actual power used by a processor? Or can I go by the TDP?

    I really wish there was a website with all this....

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    Quote Originally Posted by SKYMTL View Post
    And where would I find the actual power used by a processor?

    I really wish there was a website with all this....
    The rough hand estimate (some people like to argue with this method but when pressed none have ever provided a better method) way is to take the TDP and divide by 12 for current processors.

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    So if a Conroe has a TDP of 65W, it is only drawing 5.4W of power? What can't be right. I think its more like 5.4A unless I'm mistaken.....

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    Quote Originally Posted by SKYMTL View Post
    So if a Conroe has a TDP of 65W, it is only drawing 5.4W of power? What can't be right. I think its more like 5.4A unless I'm mistaken.....
    TDP/12v=Amps

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