Auxiliary 4-pin ATX 12V connector on Supermicro H11SSL-i

Discussion in 'Processors and Motherboards' started by Shafarevich, Sep 12, 2019.

  1. Shafarevich

    Shafarevich New Member

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    I am using a Supermicro H11SSL-i motherboard. Besides the usual 24-pin motherboard power and 8-pin CPU power connectors, the board has a 4-pin ATX power connector (circled out in the bottom left of the image below).
    Supermicro-H11SSL-i-Motherboard-with-EPYC-Layout.jpg
    The motherboard manual says it provides "auxiliary power to peripheral devices".
    MotherboardManual.png


    The PSU I am using (Corsair AX1600i) does not have such a 4-pin cable, but it provides 4+4 pin CPU power cables. Can I use one of the 4-pins from the CPU power cable to plug into this connector?

    I tried to contact Supermicro tech support about this. Their only replied that there is no need to use this connector if there are no peripheral devices requiring power. I am still a bit confused. What would count as peripheral devices requiring power? For example, if I use a PCIe card that does not have its own power connector, shall I plug this 4-pin connector of the motherboard? What is this connector intended for anyway?
     
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  2. zir_blazer

    zir_blazer Active Member

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    I suppose that it should be if you are fully populating the PCIe Slots. The main 24 Pins ATX Power connector has only 2 12V wires that supplies around 250-275W or something around that, whereas a single PCIe 16x card can draw up to 75W from the slot. Multiply that by 3, add Motherboard integrated devices, and three more PCIe Slots (1x slots are capable of 25W), and you will cerainly overload the 24 Pins ATX connector. In the early days of cryptocoin mining, there used to be a lot of cases of burned 24 Pins connectors due to that reason.
     
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  3. Mithril

    Mithril New Member

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    Many PSUs now come with the "4+4" style that can be used EITHER as a 4 pin connector OR an 8 pin connector. Verify the pinout is correct before plugging it in to be certain. One half of the "4+4" will have the right socket shape for the pins. If you look at the connector you should see that it is keyed, some of the pins have a square plastic, the others are a trapezoid.

    DO NOT try to use a PCIe(GPU) connector for motherboard power (4 or 8 pin). Unless it is actually a PCIe power plug (usually only in addition to a 8pin connector). The pinout of PCIe 12v and motherboard (cpu) 12v is not the same. There are adapters to go from one to the other (changes the pinout).
     
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  4. Shafarevich

    Shafarevich New Member

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    Thanks for the advice! BTW I found an article online that says you can use a molex-to-4pin connector if there is no 4-pin cable from your PSU:
    Screenshot 2019-09-15 at 10.25.32.png

    I guess I can simply use one of the 4-pins from the 4+4 pin cable, instead of using such an adapter?
     
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  5. Mithril

    Mithril New Member

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    Yes, the molex to 4 pin is a really bad idea, there's a reason the 4 pin plug has 2 power and 2 ground cables ;)
     
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