Powering Up: A Guide to PSU Connectors and Their Functions on the Motherboard

Modular PSU example

A power supply unit (PSU) has several cables with connectors at the end that are meant to supply power to different hardware components. Knowing which is for what can be a challenge for many. Here are some of the most important PSU connectors that you should know about:

• ATX 24-Pin Power Connector: The 24-pin connector is arguably the most important as it provides your entire motherboard with all the power it needs so as to function properly. Older motherboards required a 20-pin connector whereas newer ones need an additional four pins. That’s why this connector is divided into two parts — the 20- and 4-pin segments (so as to ensure maximum hardware compatibility). The corresponding header for this particular cable is almost always located on the right-hand side of the motherboard1.
• 8-Pin (4+4) CPU Connector: This particular connector will provide your processor with all the power it needs. That is its primary function and, well, it’s about as important as you can imagine. Now, different CPUs have different power requirements which are also reflected in your motherboard of choice. Your motherboard will have one of the following: a single four-pin header, a single eight-pin header, an eight- and a four-pin header or a dual eight-pin header1.
• SATA Power Connector: The SATA power connector is a 15-pin connector that supplies power to SATA-based hard drives and optical drives. SATA power cables protrude from the power supply unit and are meant to reside only inside the computer case. This is unlike SATA data cables, which are also usually kept behind the case but can also connect to external SATA (eSATA) devices such as external hard drives via a SATA to eSATA bracket1.
• PCI Express Connector: This connector is used to supply power to PCI Express graphics cards. Whether a graphics card requires this power supply connector will depend on its power consumption. Low-end graphics cards may not need it at all, while high-end graphics cards may require up to two such connectors to run. There are also 8-pin (6+2) PCI Express connectors that deliver more power than the regular 6-pin connectors.
• Molex Connector: This connector is used to supply power to IDE hard drives and IDE optical drives. IDE drives are going the way of dinosaurs but Molex connectors are still well and alive thanks to the following adapters that allow them to power SATA drives and computer case fans: Molex to SATA Power Adapter and Molex to 3 Pin Fan Adapter.
• Floppy Drive Connector: This connector is used to supply power to floppy disk drives. This connector has been obsolete for ages, but it can still be found on modern power supply units.