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ATX Power Connector, Motherboard.. Needs -5V, -12V?

Discussion in 'Electronic Basics' started by, Mar 7, 2004.

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  1. Guest

    I'm looking to power a PC motherboard (Via mini-itx, M10000) with an
    external DC-DC based power supply. I can provide 12V, 5V, 3.3V and
    5VBB but don't have -5V and -12V. Do you know if motherboards
    required these voltages in general?

  2. Yes. -12 is used for the serial ports (remember that RS232 uses
    bipolar signaling). -5 was, at one time, used for memory stuff, but I
    don't know if it's required any more.

    I would also point out two other things. First, what you're
    attempting has already been done, many times, by companies who supply
    parts for industrial computers. If you need a DC-DC supply for a PC, it
    can be had for about $200.

    Second: My attitude towards a design like this would be "Don't
    leave out ANY voltage, even if it is rarely used."

    In other words, if you're bent on doing this, design in both -5
    and -12. Why deviate from long-established industry practice?

    Keep the peace(es).

    Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
    (Known to some as Bruce Lane, ARS KC7GR,
    kyrrin (a/t) bluefeathertech[d=o=t]calm --
    "If Salvador Dali had owned a computer, would it have been equipped
    with surreal ports?"
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