CPU OPT vs. CPU FAN: How Do They Differ? [Distinct Comparison]

Daisy updated on Jan 11, 2024 | Home > Knowledge Center

Finding a PC that fully suits your gaming needs is very difficult, so most hardcore gamers prefer to build their gaming systems. One of the hardest and most nerve-racking things to do when building a system is connecting all the wires without making the slightest mistake. When connecting a cooling fan, you will find many different headers like CPU OPT, CPU FAN, etc.

Continue to read the article to learn more about these headers and CPU OPT vs. CPU FAN differences.

What Is CPU OPT?

CPU OPT is a 4-pin header used in some systems to work as a secondary connection for the cooling system. As clear from its name, it is an optional header used for large PC heatsinks or to connect AIO cooling pumps. Unlike the CPU FAN header, it doesn't have integrated safeguards, so it does not affect the system booting. Even if the CPU OPT header is empty, your system will work normally. In the case of your system getting hot, it will provide you with a warning of the system being overheated.

What Is CPU FAN?

CPU FAN is the primary fan header on the motherboard for the cooling system. The motherboard, BIOS, and different software (SpeedFan, HWMonitor, etc.) use this fan header to control the temperature of the CPU. It has an inbuilt failsafe to protect your system from damage. Your system will not boot if no fan is plugged into the CPU FAN header. Similarly, if the connection to the CPU FAN is disturbed when your system is already running, the system will safely shut down.


Both CPU OPT and CPU FAN are fan headers on the motherboard for connecting cooling fans to the system. Here are some of the major differences between CPU OPT vs. CPU FAN:

CPU OPT is a 4-pin header that is a secondary connection for cooling fans. CPU FAN is the primary fan connection and has a direct connection to BIOS.
It does not affect the system boot. It directly affects the system boot. The system will not boot unless a fan is connected to it.
The purpose of CPU OPT is to power the other cooling systems associated with the CPU cooler. Its main purpose is to power the CPU cooler. 
With CPU OPT, you can use splitters to channel the power to multiple devices. You cannot use a splitter to channel the power somewhere else. 


We have answered some common questions below if you still have some unanswered questions about CPU OPT vs. CPU FAN.

1. Is CPU OPT necessary?

No, connecting a fan to the CPU OPT is unnecessary. The "OPT" in CPU OPT stands for optional, so unlike CPU FAN, the system will work fine even if no fan is connected to the CPU OPT header.

2. Can I plug the pump into CPU OPT?

Yes, you can plug a pump like AIO into CPU OPT, though it is not recommended. CPU OPT is a special connection for the motherboard to keep the CPU cool at all times. So, it is better to use CPU OPT only for fans. If you connect the AIO Cooler to CPU OPT, ensure that the radiator is connected to CPU FAN.

3. Can I use the CPU OPT header for the case fan?

If the CPU OPT header is a 4-pin fan header and the motherboard can control the fan speed through BIOS and OS, then you can connect a case fan to the CPU OPT header. When connected to CPU OPT header, the case fan speed will dramatically increase if the CPU gets hot.

4. Is it ok to run the CPU FAN at full speed?

You can safely run your CPU FAN at full speed. However, it will lead to faster fan wear out. That's why it is recommended to leave the fan speed to be automatically managed by the system depending on its specs.

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Updated by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working at EaseUS for over ten years, starting as a technical writer and moving on to being a team leader of the content group. As a professional author for over ten years, she writes a lot to help people overcome their tech troubles.

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