CPU OPT vs CPU FAN: Clarifying the Difference

If you’re building your PC for the first time, you’ll need to know about what to connect to your motherboard and where. Yes, I’ve been there too. It’s not hard to get lost between all the headers and ports especially when they look all the same.

This time, we’re going to talk about two fan headers in specific. Even if we’re calling it CPU OPT vs. CPU Fan, they really don’t go neck to neck in a performance battle. However, there are some key differences.

I’ll try to explain what they are, their utility, and their function. By the end, we hope that you’ll have a clear idea about the whole thing by being able to put aside all confusion. So, let’s begin!

Defining a Fan Header

CPU fan header

I think before getting into the differences between the two types of fan headers, we need to talk a bit about what a fan header even is. The male half of a power connection can be seen on motherboards as rows of pins. These literally stick out like needles. So, it’s really hard to miss them.

On these headers, a female socket counterpart gets attached. Thus, the power connection gets completed.

Fan headers, as the name suggests, are used to provide electrical power to fans in general. They can be used to run other cooling systems on your computer as well. By cooling systems, I’m referring to AIO watercoolers like the MSI MAG Series CORELIQUID 240R or custom loops in general.

CPU_FAN and What it Does

The CPU_FAN header is known as the primary header on the motherboard. It’s basically where you need to connect your CPU cooler to. Be it a simple fan or a large one with a heatsink like the Cooler Master Hyper 212 RGB.

CPU fan

You might ask yourself, is it really important? Let’s answer that question like this: If it fails to provide power to the CPU cooler, the BIOS will prevent the PC from starting up. OR, your CPU will simply overheat and burn out.

Don’t wanna say goodbye to your CPU? Make sure the CPU_ FAN header works.

Just so you know, CPU_FAN headers are four-pin headers. This enables the fan speed to be controlled through the BIOS. This is actually necessary. Because when the CPU’s thermal sensors detect a certain rise in temps, the fan needs to act accordingly. This can also be done by desktop software or the OS.

Key Fact

Surprisingly, unlike the other headers of the motherboard, the CPU_FAN header has to remain connected to a fan. Otherwise, the computer simply won’t boot. Plus, any malfunction or disconnection of power with this fan header will result in an automatic shutdown.

CPU_OPT and Its Purpose

The CPU_OPT header is better known as an optional power header. The OPT in the name actually stands for optional. This acts as an additional source of power for coolers with larger heatsinks. As I said before, it can be used to power AIO/ Liquid coolers.

CPU opt

Keep note that these aren’t generally connected with the primary CPU cooler. CPU_OPT headers are 4-Pin ones as well. This means they can be made to act accordingly with temperature increase and decrease.

Key Fact

A major difference between CPU_OPT and CPU_FAN headers is that it doesn’t affect the PC boot in any way. Even if the cooling system is connected to this one and it starts malfunctioning, the PC won’t shut down. So, it can be said that they are inferior a bit in the safety department.

(You might get warnings regarding issues with the connected hardware though.)

How to Create the Connection

Now that you know pretty much about the details and functionality Let’s discuss a bit about the ways to connect them to an actual female port.

Connecting CPU_FAN

As I’ve said before, there’s really no alternative way to do this. The main CPU cooler will be connected through the female socket with the CPU_FAN male header. Just make sure the pins go through the socket properly. Don’t apply extra force. You DON’T want a broken CPU_FAN header.

Connecting a CPU_OPT

Well, this one pretty much goes just like the CPU_FAN header. The only probable difference here is that you can use a splitter to power multiple fans from the CPU_OPT.

Key Differences



Has a direct connection with the BIOS and affects PC boot and shutdown. Used as a common 4-Pin fan header and doesn’t affect PC boot or shutdown.
Originally made to power the CPU cooler. Primary purpose is to power other cooling systems associated with CPU cooling.
A splitter can’t be used to channel power elsewhere. Splitters can be used to provide power to multiple devices.


Here are some pretty common questions that get asked regarding CPU OPT Vs CPU FAN. Let’s answer them, shall we?

Can I power a pump with a CPU_OPT?

Yes, it’s very much possible. This can work nicely with an AIO cooler. The CPU OPT, CHA FAN, or SYS FAN headers are great for this purpose. All you have to do is ensure that the radiator is connected to the CPU_FAN.

Is it possible to connect a fan hub into a CPU_FAN or a CPU_OPT?

Technically yes, you can. But it’s best not to use the CPU_FAN for anything else than the CPU itself. Also, you might want to take one that draws power externally from the power supply. Why take the risk?

Will a 4-Pin fan work on 3-Pin?

Yes, it will. But you won’t be able to control the fan speed. The fan will run at full speed all the way.

Closing the Discussion

I really don’t think I’ve left anything behind. I’ve gone through all the details to give you a complete overview on the “CPU_OPT vs CPU_FAN” topic. The questions on your mind should be answered by now.

So, let’s wrap it up for now. I hope you don’t fall into trouble when connecting the fans or understanding the particular header’s purpose. With that said, I bid you farewell.

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