GA-M59SLI-S5 - Power connect

Discussion in 'Gigabyte' started by craigq, Oct 23, 2006.

  1. craigq

    craigq Guest

    I have a GA-M59sli-s5 MB, Gigabyte GV-NX73T256p-RH Video card, AMD
    Athlon 64 X2 4600 AM2

    The MB has a ATX_12V_X2 power connect - and an ATX 24P Powerconnect.
    What is the difference between these 2 powerconnects. Is one "better"
    than another?

    I also have a 4 pin powerconnect on the MB labeled PCIE_12V - do I need
    this powerconnect for the video card I have?

    Thanks
     
    craigq, Oct 23, 2006
    #1
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  2. craigq

    Paul Guest

    ATX_12V_2X powers the processor only. It is a 2x4 connector, although
    I don't know why they put that on the motherboard. Obviously, someone
    feels a high power processor of some sort is going to be used. Maybe a
    quad core some day will need it ?

    You can plug a 2x2 power connector into the 2x4 connector. The 2x2 connector
    has 2 GND pins and 2 +12V pins. Each 12V pin is rated for 6 amps, for a total
    of 12 amps capacity. Doing the math, 12V * 12A = max power flow of 144W. If
    we assume the Vcore voltage converter on the motherboard is 90% efficient,
    the max power the Vcore could convert would be 144W x 0.90 = 129.6W . That
    should be enough for a 125W FX-62 processor. So for any existing processor,
    a 2x2 connector would do the job.

    Your X2 4600+ AM2 uses either 65W or 89W, depending on version. Well
    within the limits of a 2x2 ATX_12V type connector.

    The main 24 pin connector powers the motherboard. There are 3.3V, 5V, and
    12V rails on the connector. Those are the main power consuming rails. There
    are a few more voltages on there, where not a lot of current is drawn.

    When a lot of current needs to flow, you want a low resistance path. That
    is why the main 24 pin connector has so many pins and wires. There are
    two 12V pins on the main connector. And those provide current to the PCI
    Express x16 slot connectors, for example. Video cards can draw up to
    about 120W, which is 12V @ 10A. With a mega card like that, the current
    is split, and some flows via the PCI Express slot connector, and some
    flows via an Aux power connector on the end of the video card. The
    PCI Express video card slot connector can supply a max of a little more than
    4 amps. The other 6 amps, if needed, would flow through the Aux connector.
    The Aux connector could be a 2x3 "official" PCI Express connector, or
    you could also use a Molex 1x4 disk drive connector for a video card
    design.

    Since an SLI motherboard has room for two video cards, then a total of
    8 amps could flow for video. Motherboards usually have fan headers, and
    you might get 0.5A flowing for some fans. That is a total of 8.5A from
    12V, and that is flowing through two 12V pins on the 24 pin main
    connector. The two pins are rated for a total of 12A, so the 8.5A for
    a maxxed SLI setup would be handled easily by the pins. If you
    plugged a 20 pin connector into the 24 pin connector, then only one
    12V pin makes contact, which is fine if only one video card is installed
    in the motherboard. But once you get two video cards in the motherboard,
    then it is time to think about a power supply with a 24 pin connector.

    Your motherboard also has a PCIE_12V connector near the bottom edge
    of the motherboard. That is intended to add to the current capacity of
    the main 24 pin power connector. You could, for example, use a 20 pin
    power connector for the main power, and connect a disk drive connector
    to the PCIE_12V connector, and that would also be able to carry more than
    12A to the video card(s). And since the motherboard has room for three
    video cards (third GPU as physics card perhaps?), the PCIE_12V disk
    drive connector might also come in handy for some extreme loading
    condition in the future.

    I would say the motherboard is built like a battleship, and considering
    your current hardware config, not all of these connector schemes need
    be fully utilized.

    For your 4600+ processor and 7300GT video card, you may connect:

    1) 20 pin or 24 pin main connector. A single video card does not
    need a heavy current flow. Using a 20 pin power connector would
    be sufficient. Using a 24 pin power connector would also work.

    2) A 2x2 connector to the 2x4 ATX_12V_2X connector, is enough for
    your processor. The 2x2 goes on the right hand side of the 2x4.
    Your motherboard manual explains this in enough detail. You may
    also use a 2x4 connector if your power supply has one. If the
    power supply 2x4 documentation says the connector has 12V1 and
    12V2 pins on it, then don't use it. All the pins on one side of
    the 2x4, should be connected to the same 12V rail, not to two
    different rails. Using a 2x2 power connector avoids this issue
    entirely.

    3) PCIE_12V does not need to be connected.

    I would use all the power connectors, if you buy a quad core
    processor, and three video cards :)

    HTH,
    Paul
     
    Paul, Oct 23, 2006
    #2
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