Basics on CPU Fan Headers and Their Purposes

If you’re among the many people who opt to build their own PC, there are several areas where you’ll need some basic knowledge to move forward. One of these is with regard to various fan headers that will be present on your motherboard, two of the most notable of which are your CPU FAN headers and CPU OPT fan headers.

At Xidax, we’re proud to offer a variety of services to clients looking to build custom gaming desktops or laptops, plus many other computing setups you might be interested in. We’ll assist you with every part of your setup, from the motherboard and other important CPU elements to hardware, software and even numerous accessories like monitors and others. What are the CPU FAN headers and CPU OPT fan headers in your motherboard, and what are some basics on using each of them and a couple of their other varieties? Here’s a primer on these important components.

Fan Header Basics

First and foremost, a quick word on fan headers in general so you understand the realm we’re entering into. Fan headers are rows of pins found on a computer motherboard, forming the “male” half of a power connection. The “female” half would be a device like a fan.

If you ever go inside the tower of your computer, you should see some extra wires coming out from where the motherboard is installed; these are for fans. Of course it’s an oversimplification, but this essentially explains what we’re talking about here.

Fan headers basically allow for simple cooling and similar needs without the need for a fan controller – though they can work in conjunction with these devices if you wish. Fan headers may also be used to power water cooling systems and the like.

And as any long-time computer user knows, cooling is a vital part of keeping your system running optimally. Without proper cooling, you could end up with fried hardware. Let’s read on to learn more about specific fan headers found in your motherboard.

CPU FAN Header

Known in the computing world by the abbreviation CPU_FAN, the CPU FAN header is the primary and most important header found on your motherboard. It’s the one that plugs directly into your CPU cooler, and it’s the one that will control your CPU fan speeds.

If this is not done, your machine’s BIOS will not allow the computer to boot — and that’s the best-case scenario. In a worst-case scenario, the computer will attempt to run, but will overheat quickly, leading to some hardware damage.

So here’s the crucial thing that you absolutely need to know about your CPU FAN header: it provides both power and data to your CPU cooling unit. When you plug in a CPU fan, this is where it will go, basically forever.

This fan header also differs from others on the motherboard in a few ways. The first is the issue we went over above: That you will not be able to boot the device in most cases if the CPU FAN header is not plugged in. There are also others, however, including:

• If your computer is already running and the connection to the CPU FAN is disrupted, the system will automatically shut itself down to avoid damage.
• If you’re using a CPU fan that isn’t extremely powerful or somewhat unusual in some way, the motherboard will warn you at boot time that it couldn’t detect a fan and to check your system immediately.
• Nearly all CPU FAN headers are 4-pin in nature, meaning the speed of their fans can be controlled by several different sources: The BIOS, the Operating System, or even certain desktop software specifically designed to control fan speeds.

CPU OPT Header

Abbreviated CPU_OPT, and short for CPU Optional, the CPU OPT header is a secondary power header that provides additional power and data to your CPU fan unit. This is not required for many units, but if you do need it (and some might) the fact that it exists is important.

CPU OPT headers will most often be used for larger CPU heatsinks, or for power liquid cooling systems that aren’t the primary form of cooling. The major difference between the CPU OPT header and the primary CPU FAN header is the fact that the OPT header does not prevent the PC from booting if it is not connected; similarly, if the device is already on, it will not shut down as a result of a disconnected CPU OPT header. At the same time, some consider this a negative, as it removes an important safeguard against CPU fan failure.

As the name suggests, the CPU OPT header is optional, and most users will never need it. Its main purpose is to provide additional power to devices that need it, which can be helpful in overclocking or other situations where more power is required.

CPU OPT headers are typically 4-pin, just like the CPU FAN header, but they are often on the opposite side of the motherboard, particularly if it’s an ATX model. They can also be 4-pin or 3-pin in nature, depending on their location.

CHA_FAN and SYS_FAN Headers

There are also two other fan header formats to be aware of:

• CHA FAN: Short for chassis fan, the CHA_FAN header is used for your system’s internal fans. In most cases, case manufacturers will provide a cable that has two female fan headers on either side of the cable. This can be plugged into several different locations in your system, but is typically located near the CPU area to supply cooling for your motherboard and other components inside the case.
• SYS FAN: Abbreviated for system fan, the SYS_FAN header is intended for your system’s power supply. This is built to work with high-end power supplies that have their own integrated cooling unit inside of them, and as such it is not necessary on most models, particularly those intended more for office or home use.

Most motherboards will have at least two of these fan headers, and some as many as six. It’s important to be aware of their location and function so that you can purchase the correct fans to match them.

For more on CPU FAN headers and various related items, or to learn about any of our custom gaming computers, speak to the staff at Xidax today.