Power supply information.Last updated: July 15, 2008 All about the various PC power supply cables and connectors The various power supply cablesGeneral infoIf you'd like more technical data about ATX power connectors then you canfind the current specifications and more atWires and connectors are not perfect conductors. They have resistance. Whencurrent passes through wires and connectors there is a voltage drop and thatenergy is lostas heat. As long as you don't overload them the voltage drop and extra heatdon't matter. But the losses get worse as the current rises. That's why yousee some power cables with more that one wire for the same voltage. Havingmultiple wires reduces the losses.

• Atx Power Connector

If you seriously overload a line, the wirecan get fairly warm. The resistance of connectors tends to increase as theyare plugged and unplugged so after enough uses they can overheat and evenmelt when passing a large current.

So a lot of changes in connectors overtime has to do with adding more wires and connectors to make sure that noneof these problems occur.Some of the tables below provide the maximum wattage supported by a powercable and its associated power connector. Some specifications clearly spellout the maximum allowed wattage. Otherspecifications just provide the suggested connector and wire gauge and neverspecify a maximum wattage. And there's never really an absolute value to themaximum wattage anyway. If you draw a little more wattage then the maximum,the hardware doesn't immediately burst into flames. Thevoltage drop and power dissipation increase as you increase thecurrent so there isn't a clear maximum wattage at which it stops working.Most of the specifications which spell out the maximum wattageprovide a wide safety margin by defining a valuewhich is far below the maximums supported by the connector and wire.

If the table below provides an 'Officialcable/connector maximum wattage' then that specification has spelled out themaximum wattage. In most cases that wattage will be significantly below whatcan actually be handled by the suggested connector and wire.

If the tableprovides an 'Unofficial cable/connector maximum wattage' then thatspecification doesn't provide the maximum and the value in the table is apractical maximum wattage defined by the maximums for the connector and thesuggested wire. An unofficial wattage doesn't have a wide safety marginbuilt in because people differ on how much margin to provide. Some peoplehappily use connector and wire maximums and other people like to have a widesafety margin.Power connectors included with various kinds of PCsVersionIntroduction dateIncluded connectorsPC1981ATX1995ATX12V 1.02000ATX12V 1.32003ATX12V 2.02003EPS12V2003PCI Express 2.02007Original PC main power cablesThe original PC debuted in 1981 and used two cables to connect thePSU (power supply) to the motherboard. The two cables plugside by side into the motherboard connectors. Sometimes they are keyed sothey only plug in one way and sometimes they aren't. Even if they're keyedyou can insert them the wrong way if you put a little effort into it.

Youalways have to remember to plug them in so the black wires are next to eachother.

Atx Power Connector

The keying is slightly different, but the PCIe power plug fits easily into the ATX 12v socket; the difference in the keying is only one pin (pin 5 from the diagram in your link), which is D-shaped instead of square on the PCIe power connector, so it actually inserts fine into the square socket on the motherboard. Or at least it does on the MSI Z77A-G41 I'm working on.Of course, the 12v and ground wires are essentially reversed on the two connectors, so using the PCIe power cable on the ATX 12v soket would likely fail spectacularly.