Your PC’s Power Cables Explained

So, you are building a new gaming PC. For a newcomer, it can be a daunting task. After all, there are many components, and if you don’t know what you’re doing, you can mess it all up. As such, it’s important to be familiar with all the components inside a PC, how they work, and what goes where.


Example: the power supply you just unboxed and the jumble of cables sticking out of it. What are all those PSU cables and connectors, and what are they for?

20/24 pin motherboard cable

First, the cable that probably caught your eye the most is the wide 24-pin, whether you purchased a modular or non-modular power supply. And it’s actually the most important cable.

This cable is the main connector that provides power to your PC’s motherboard. While it’s not the only connector your PC needs (other components will require additional power, as you’ll soon see), it’s the primary one responsible for supplying the correct voltage to your motherboard, and by extension , to most components of your PC . This includes your RAM, storage devices, PCIe devices without auxiliary power, and just about everything else on your motherboard.


You will normally find this connector prominently on the edge of your motherboard. On older ATX motherboards, as well as lower end boards, you’ll find that the main connector actually has 20 pins instead of 24. Also, some power supplies come with a 20+4 connector (with 4 pins which can be separated) instead of a simple 24 pin. Indeed, older PCs with lower power requirements can make do with 20 pins instead of 24, and power supplies have remained the same over the years (and not for lack of trying).

PSUs are more or less backward compatible thanks to the ATX standard, and this has stuck in the minds of some PSU manufacturers. After all, old power supplies eventually die, and when they do, the ability to use a new power supply can likely save it from ending up in a landfill.

4/8 pin CPU connector

Next we have the CPU connector. The processor is one of the few parts of your PC that requires auxiliary power in addition to the power supplied to your motherboard. The CPU connector is there to intervene.

The CPU connector is normally near the CPU socket of your PC. Just plug it in once you’re done with your motherboard connector, and you’re good to go.

Depending on the computer, you may find this connector a little different. In low-end PCs, you will find a 4-pin connector on your motherboard, which should be able to supply enough power for those low-end chips. On mid-range and high-end CPUs, you can expect to find an 8-pin instead, giving enough power to almost any chip.

Almost always, your PC’s power supply will include an 8-pin connector that breaks in two, called 4+4 pin. This allows it to be connected to both 4-pin and 8-pin connectors – just put one aside if you don’t need to use it.

In some power supplies you can find several CPU cables. Similarly, some motherboards may include an 8-pin connector and a 4-pin connector or have a 12-pin connector instead. Although not the norm, some PCs need a lot of CPU juice, especially for people who like to overclock.

PCI Express 6/8 pin cable (GPU cable)

Technically, all PCI Express power requirements are already served by the connector on the motherboard. After all, if you put something like a Wi-Fi card in it, it will work just fine. However, some devices (most often GPUs) need additional auxiliary power in addition to what the motherboard provides. This is where PCIe cables come in. These are sometimes referred to as GPU cables because they are primarily used by GPUs.

They will be available in 6-pin and 8-pin flavors and will connect above a GPU. Depending on the GPU we’re talking about, you might get by with just one connector, or you might need two or even three, depending on the power requirements of the specific card. If a card’s power requirements are not fully met, users may experience performance drops or even instability and frequent crashes. Luckily, most power supplies, especially higher wattage ones, come with multiple power cables.


Other power cables

While these are the three main cables you should be aware of, there are others you may or may not need depending on your use case. These are responsible for powering the secondary components of your PC.

SATA cable

First up we have the SATA power cable. These are still widely included in power supplies these days, and if the name SATA gives you any clues as to what it’s used for, then your hunch is probably correct. The SATA power cable is mainly responsible for powering a SATA hard drive or other drive directly from the hard drive. It should not be confused with the SATA cable, which is the real connection between your hard drive and your PC: the SATA power cable provides the power, while the SATA cable provides everything else.

Lately, SATA power cables have also seen other uses. For example, some computer cases with addressable RGB may have a hub to connect all cables from RGB devices, such as fans. In this case, that RGB hub will likely be powered by a SATA power cable, even though it’s not a drive. It can be used as an auxiliary power supply for many devices.


Molex

Molex is largely retired these days, but you may still see it on older or lower-end PCs. Like SATA, Molex connectors are intended to provide you with auxiliary power. Molex connectors were once found in everything from hard drives to case fans.

Over the past decade, however, Molex has largely disappeared. The reason? It’s generally seen as an annoying connector to deal with, breaking easily and being generally unreliable. Use cases that still require Molex-style auxiliary power have since moved to SATA.

Know your PC’s power supply

In order to be able to build your PC the right way, it’s essential that you know what each power connector coming out of your power supply does, just as it’s important to know how efficient it is. Hopefully with our explainer it’s clear enough now.

Alan A. Seibert