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ATX_12V_2X and PCI_EXPRESS_16 power leads

Discussion in 'PC Hardware' started by Keith Beef, Oct 23, 2007.

  1. Keith Beef

    Keith Beef Guest

    Hi, all.

    I'm putting together a new system, with a Gigabyte P35-DS3P motherboard in
    a full tower case.

    I've just noticed that the ATX_12V_2X cable from the PSU is too short
    (at 53.5cm) to reach. It would need to be around 15cm longer to
    comfortably reach without hindering air flow or access to other components.

    This is a PSU with "modular" leads, i.e. the lead in question
    connects to a socket on the PSU.

    So the question is, is it worth trying to buy a longer lead, or can I get
    buy without? The CPU is an Intel Q6600, the PSU is a Thermaltake
    W0106RU (rated 700W).

    Also, for a single video card in a PCI Express 16X slot, do I really need
    the extra power lead which seems to go from the PSU to a 4-pin molex
    connector on the motherboard? Or the lead which would go from the PSU
    direct to the video card edge connector (requiring an adaptor)?

    Am I right in thinking that these two leads are only necessary when two
    cards are present in an SLI setup?

    Keith Beef, Oct 23, 2007
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  2. Keith Beef

    Arno Wagner Guest

    You cannot get by without. Even if the 12V lines in the ATX connector
    supply the CPU, these would get seriously overloaded and likely melt
    and may cause a fire. For this reason typically the CPU is supplied
    only by the extra connector.
    You do not need the 4 pin molex, unless you have an older, high-powered
    graphics card, that does not have its own power connector on the card.

    You absolutely need to use the connection directly to the card if it
    is present. Here, it is unlikely that you kill anything if you do not
    use it, but the card draws most of its power from it and will simply
    not work if you do not plug the extra connector in.

    My take is that you bought a very badly designed tower case. The
    PSU should sit directly above the mainboard. For ventilation
    at the top, an extra fan shoul be used.

    Side note: These connectors cost real money. They can each
    transport something like 200W. Do you think they would
    put them in if they were unneeded???

    Arno Wagner, Oct 23, 2007
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  3. Keith Beef

    Keith Beef Guest

    What I meant here, was:
    1. the PSU -> Molex connector
    2. the PSU -> PCI Graphics card edge connector
    Thanks for the information, Arno.
    Keith Beef, Oct 24, 2007
  4. Keith Beef

    Arno Wagner Guest

    Oops, sorry. I thought you meant two times 2.
    No, I am pretty sure the molex is only necessary
    for a card that does not have 2. The PCI graphics card
    edge connector needs to be used whenever it is present.
    No problem.

    Arno Wagner, Oct 24, 2007
  5. Keith Beef

    Keith Beef Guest


    Now I'm a bit stuck. My video card didn't come with an adaptor to connect
    a Molex 4-pin to the edge connector.
    As usual, the documentation is vague (to say the least)... I often get the
    impression that a manual is written in such a way as to be generally
    applicable to a dozen models, and specifically to none.

    Keith Beef, Oct 25, 2007
  6. Keith Beef

    Keith Beef Guest

    After more scouting around, I find that the edge connector is NOT for
    power... It is the SLI connector!

    I suppose I need to supply power to the molex connector on the mainboard,

    Keith Beef, Oct 25, 2007
  7. Keith Beef

    Arno Wagner Guest

    Ahhh. If it is is shaped from the PCB, then it is indeed the
    SLI connector. A PCI-E power connector looks like this:


    Sorry again for misunderstanding. Yes, I think yiu should
    use the molex on the mainboard.

    Arno Wagner, Oct 25, 2007
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