Everything You Need to Know About Power Supplies

Power Plugs

Nowadays, power supplies provide the following connectors to feed the components from the PC:

• Main motherboard connector: This is one of the cables that you need to connect to the PC motherboard. It uses a big 24-pin plug, which is the biggest plug found on the power supply. Most power supplies will allow you to convert this 24-pin plug into a 20-pin plug (usually by removing the extra 4 pins), which is the standard used by older motherboards. Motherboards that use the 24-pin connector are called ATX12V 2.x, while motherboards that use the 20-pin connector can be either an ATX12V 1.x motherboard or an ATX motherboard. Note that these names refer to the electrical connection of the motherboard and not to the motherboard’s physical size. ATX is also a name used to describe the size of the motherboard, which can be confusing for some users (you can have an ATX motherboard with an ATX12V 2.x connector). For example, in this case ATX refers to the size of the motherboard, 12” x 9.6” or 30.5 cm x 24.4 cm.

Figure 6: Main motherboard connector (24-pin plug). See how it can be transformed into a 20-pin connector.

Figure 7: Main motherboard connector (24-pin plug).

• ATX12V connector: This 4-pin connector is used to provide electrical current to the system CPU and must be installed on the motherboard. The installation of this connector is required – unless you use the EPS12V connector (see below).

Figure 8: ATX12V connector.

Figure 9: ATX12V connector.

• EPS12V connector: This 8-pin connector has the same function as ATX12V, i.e., to provide electrical current to the system CPU. Since it has eight pins instead of four, it is capable of providing more current. Not all power supplies and not all motherboards come with this connector. On some power supplies, the EPS12V connector is obtained by putting together two ATX12V connectors. If your motherboard and your power supply both have this connector, use it instead of using the ATX12V one. Motherboards that come with this connector often come with half of the connector covered with a sticker or a plastic cover, allowing you to use the power supply ATX12V connector on the motherboard EPS12V connector. You can install the ATX12V connector from the power supply on the EPS12V connector on the motherboard, however this isn’t recommended.

Figure 10: EPS12V connector.

Figure 11: On some power supplies, the EPS12V connector is obtained by putting together two ATX12V connectors.

Figure 12: EPS12V connector on a motherboard.