The two plugs described below aren’t used anymore but you may find them while disassembling old PCs.

• Motherboard six-pin auxiliary power connector: this connector was released together with ATX12V 1.x specification, but only a few motherboards (most notably socket 423 and early socket 478 boards) used it.

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Figure 21: Six-pin auxiliary power connector.

• Motherboard 12-pin connector: This connector was the main motherboard connector on AT motherboards and AT power supplies. It became obsolete with the introduction of the ATX standard. It used two six-pin connectors and the problem was that these two six-pin connectors could be inserted on any side of the 12-pin connector found on the motherboard. In order to avoid mistakes you must install these connectors in a way that the black wires are placed on the center of the connector, see Figure 22.

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Figure 22: AT power connector.