page_title: Power supply unit (computer)
section_title: Connectors
hierarchical_section_title: Power supply unit (computer) / Appearance / Connectors
caption_attribution_description: English: Molex female connector. Español: Conector Molex hembra. Русский: разъём Molex, розетка Deutsch: Molex-Stecker, weiblich.
context_page_description: A power supply unit converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage.
  Most modern desktop personal computer power supplies conform to the ATX specification, which includes form factor and voltage tolerances. While an ATX power supply is connected to the mains supply, it always provides a 5 Volt standby voltage so that the standby functions on the computer and certain peripherals are powered. ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power up and boot. The most recent ATX PSU standard is version 2.31 as of mid-2008.
context_section_description: Typically, power supplies have the following connectors (all are Molex (USA) Inc Mini-Fit Jr, unless otherwise indicated):
  ATX motherboard power connector (usually called P1): This is the connector that goes to the motherboard to provide it with power. The connector has 20 or 24 pins. One of the pins belongs to the PS-ON wire (it is usually green). This connector is the largest of all the connectors. In older AT power supplies, this connector was split in two: P8 and P9. A power supply with a 24-pin connector can be used on a motherboard with a 20-pin connector. In cases where the motherboard has a 24-pin connector, some power supplies come with two connectors (one with 20-pin and other with 4-pin, i.e. 20+4-pin form) which can be used together to form the 24-pin connector.
  12V only power connector (labelled P1, though it is not compatible with the ATX 20 or 24 pin connector): This is a 10 or 16-pin Molex connector supplying the motherboard with three or six 12 V lines with common returns, a 'supply OK' signal, a 'PSU ON' signal and a 12 or 11 V auxiliary supply. One pin is left unused.
  12V only System monitoring (P10): This is a 171822-8 AMP or equivalent connector carrying a supply to the PSU fan and sense returns.
  ATX12V 4-pin power connector (also called the P4 power connector). A second connector that goes to the motherboard (in addition to the 24-pin ATX motherboard connector) to supply dedicated power for the processor. 4+4-pin For the purpose of backwards compatibility, some connectors designed for high-end motherboards and processors, more power is required, therefore EPS12V has an 8-pin connector.
  4-pin Peripheral power connectors: These are the other, smaller connectors that go to the various disk drives of the computer. Most of them have four wires: two black, one red, and one yellow. Unlike the US standard mains electrical wire color-coding, each black wire is a ground, the red wire is +5 V, and the yellow wire is +12 V. In some cases these are also used to provide additional power to PCI cards such as FireWire 800 cards.
  4-pin Molex (Japan) Ltd power connectors (usually called Mini-connector, mini-Molex, or Berg connector): This is one of the smallest connectors that supplies a 3.5-inch floppy drive with power. In some cases, it can be used as an auxiliary connector for Accelerated Graphics Port (AGP) video cards. Its cable configuration is similar to the Peripheral connector.
  Auxiliary power connectors: There are several types of auxiliary connectors, usually in 6-pin form, designed to provide additional power if it is needed.
  Serial ATA power connectors: a 15-pin connector for components which use SATA power plugs. This connector supplies power at three different voltages: +3.3, +5, and +12 V, in three pins per wire, one designed to precharge capacitive loads on for hot-plugging designed backplanes.
  6-pin Most modern computer power supplies include six-pin connectors that are generally used for PCI Express graphics cards, but a newly introduced eight-pin connector should be seen on the latest model power supplies. Each PCI Express 6-pin connector can output a maximum of 75 W.
  6+2-pin For the purpose of backwards compatibility, some connectors designed for use with high end PCI Express graphics cards feature this kind of pin configuration. It allows either a six-pin card or an eight-pin card to be connected by using two separate connection modules wired into the same sheath: one with six pins and another with two pins. Each PCI Express 8-pin connector can output a maximum of 150 W.
  An IEC 60320 C14 connector with an appropriate C13 cord is used to attach the power supply to the local power grid.
caption: 4-pin peripheral power connector
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