CPU OPT vs CPU FAN – Which header should you use?

When building your PC, you must understand the distinction between CPU Opt vs CPU Fan header on the motherboard. 

The primary difference between a CPU Opt and a CPU Fan header is that, unlike CPU Fan, CPU Opt headers cannot prohibit your PC from launching or immediately shut down when they don’t identify a functional CPU cooler. Thus they lack a strong defense in terms of processor cooling.

So, what exactly are these two headers? What distinguishes them? Both CPU Opt and CPU Fan headers are explained in this article, and we’ve included some detailed info about the other headers on your motherboard so that you can make an informed decision.

CPU Opt vs CPU Fan

There are several cooling fans in your computer’s CPU. These fans keep the CPU from overheating, allowing your computer to perform smoothly. Using a CPU cooler can also prevent excessive heat and associated damages. When you open the CPU, you’ll find two markings on the motherboard: “CPU_FAN” and “CPU-OPT.”

It’s easy to work with these two headers. In the CPU FAN header, you should always insert the core CPU cooling units. To ensure additional safety, you should only use it for the central cooling unit. Another use for CPU Fan is for mounting a CPU heatsink or CPU radiator.  

The CPU OPT header is required to use several cooling systems or fans to keep your device cool. You can leverage a direct cable connection if you have one supplementary fan. Cable splitters can also be used to split and connect all of your secondary fans through the CPU OPT header. The heater can also be connected to the water-cooling pumps. The CPU OPT header is the ideal option if you want to use a Fan hub.

In a nutshell, CPU Fans and CPU Opt have different functions. Therefore, when selecting a fan or cooling unit for a header, you must do so carefully.

What is CPU Opt

Due to the CPU’s volume of work, certain devices require more than one CPU fan. Such situations demand the use of more than one header. This can be beneficial if you plan to use an AIO/Liquid cooling system in addition to the primary cooling system. 

You should choose CPU OPT if you have more than one CPU fan. It’s a secondary header that connects the extra fan. An “OPT” is an abbreviation meaning “optional.” So the fan attached to this header is the auxiliary cooling fan. 

Even if you don’t have a fan attached to this header, your CPU will run properly.  If your device is overheating, CPU-Opt can alert you. Like CPU FAN, CPU OPT does indeed have a 4-pin structure. 

Since the CPU temperature is being monitored, the fan speed can also be adjusted to suit the situation. Use both of these headers if you require more than one fan to cool down your CPU. Using both CPU FAN and CPU OPT ensures that your CPU remains in excellent working order. In addition, it guarantees that your device receives adequate cooling during periods of high demand, such as during demanding work hours.

What is CPU Fan

What exactly is a CPU fan? Your system’s motherboard is connected to this tiny fan or cooling unit. It’s the CPU fan’s job to keep everything from the motherboard to the BIOS cool, as well as the CPU’s temperature. 

Different words have different meanings when it comes to “CPU FAN.” The motherboard and additional programs like HWMonitor, NZXT CAM, etc., use this header to adjust the fan’s speed to keep your CPU from excessive heat. This is the header where you should connect the CPU cooling fans. The fan will cease to work if it is not connected to the CPU Fan header. It will also prevent you from safely booting your computer. 

By regulating the fan speed, the “CPU FAN” allows the CPU to keep operating. Your gadget will shut down promptly if any fan is disconnected from it. This header has four pins, to render the best possible voltage and fan speed.

What Are CHA_FAN & SYS_FAN Headers

CHA FAN (chassis fan) is a header that facilitates the connection of a chassis fan. The chassis fan is a fan that is linked to the PC case’s exterior box. It is suitable for external or internal mounting. Toward the case fan, this pin connects from the motherboard. The CHA FAN can be 3-pin or 4-pin type. Although three-pin connectors are commonly used, it is the four-pin connectors that offer improved cooling and throughput. 

The SYS-FAN header is intended for use with the system fan. As the motherboard heats up, the fans turn on and off accordingly. SYS FAN header also enables the system fans to run at a constant speed. 

Cool air is sent into the CPU, while heated air is expelled outside via the SYS FAN device. When using a high-end graphics card, it’s best to utilize a system fan plus a chassis fan. These two things will keep your device cool and help efficiently direct the airflow.

Overall, SYS and CHA fan headers are independent and do not need to be connected to either of your cooler’s principal fans. Your computer case’s thermals will still be monitored effectively by these headers even if you regulate them on your own.

CPU Fan vs Opt Fan – What’s the Difference?

They’re both used to connect CPU cooling fans to the motherboard headers and ports. So what’s the difference between CPU Opt and CPU Fan?

There are, obviously, two significant differences. 

First and foremost, the CPU FAN header is essential in the Linux kernel. If this header fails, your computer will not be able to start. Instead, it will stay inaccessible for the time being. The CPU OPT header, on the contrary, is optional. This means that you may leave the extra fan out of your CPU, and it will still work. 

The second difference is that the CPU FAN header can tell whether or not the main fan is running accurately. In the case of a problem, the system will notify you and shut down automatically to prevent any damage. However, the CPU OPT header can only tell you if your device is nearing damage but won’t shut down the system to avert it.

How to Use CPU Opt and CPU Fan

Want to connect your CPU radiator’s primary fan? Use the CPU Fan. Nowadays, your CPU cooler or radiator can have two fans. In which case, you need to use the CPU Opt for the second fan. Are you catching our drift here?  

You can link the primary CPU cooler to the female socket using the CPU Fan male header. Make sure that the pins are correctly inserted into the socket. Don’t use too much force. There’s nothing worse than a damaged CPU FAN header. So, do the task gently. Your CPU fan should be aimed in the right direction to ensure enough ventilation. As long as you read the directions, installing these fans won’t be a big deal. 

The CPU OPT header should be used to power multiple fans from your CPU cooler, either by using a single connection cable (if you have one extra fan) or by using a splitter to allow several fans to be driven by the CPU OPT.

Frequently Asked Questions

Now that we have explained the difference between CPU Opt vs CPU Fan, it is time to get to some other related questions.

Can I use CPU opt for a fan?

You can use the CPU to opt for an extra fan or multiple fans for your system cooling, but you should not connect the primary cooling fan. For the primary fan, you should always depend on CPU_Fan, not CPU_Opt.

Can you change CPU OPT fan speed?

Connecting your case fan to the CPU OPT header will raise the case fan’s airflow or speed considerably when the CPU heats up, much like the CPU FAN header will. The speed of the case fan connected to the CPU Opt header starts to reduce as the CPU begins cooling off. This means that you can’t control or change CPU OPT fan speed; it solely depends on the thermals of your system.


Both the CPU Fan and the CPU Opt are essential components of the motherboard. Although they are significantly different from one another, CPU coolers use both of them. We hope this guide helps you better understand the usage, requirements and differences between CPU Opt vs CPU Fan. Let us know in the comments!

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About Melissa

Hey! I'm Mel, I write the occasional article for Spacehop, amongst other things. I love meeting new people and chatting, so if you have any questions don't hesitate to ask.

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