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CPU_FAN vs. CPU_OPT on Motherboards: What is the Distinction?


Key Takeaways

  • Use the CPU_FAN header in your motherboard to attach your CPU cooler, because it adjusts fan pace based mostly on CPU temperature.
  • The CPU_OPT header is for a secondary CPU fan, however you need to use it for added case followers. It has the identical performance as CPU_FAN.
  • SYS_FAN and CHA_FAN are for case followers.


You may come throughout many similar-looking fan headers when looking for your approach across the motherboard to connect with the CPU cooler. And whereas the printed labels may help you navigate the motherboard, they don’t seem to be precisely descriptive. For instance, what does CPU_FAN and CPU_OPT even imply?


Use CPU_FAN for Your CPU Cooler

The CPU_FAN (additionally CPUFAN, CPU_FAN1, and so forth.) header in your motherboard is a four-pin fan header that your pc makes use of to energy and management the CPU cooler. It is often discovered on the appropriate aspect or above the CPU socket.

Virtually each motherboard has this common header, and practically each CPU cooler makes use of it. It really works like every other four-pin fan header, that means it will possibly use pulse width modulation (PWM) to regulate the fan pace. The one distinction is that it is labeled as a CPU fan connector that can assist you differentiate it from different fan headers, and it will modify the fan pace based mostly on the CPU temperature by default. Nevertheless, you possibly can change the CPU fan temperature enter within the BIOS.

If you happen to’re constructing a brand new pc or simply tinkering round, join your CPU cooler to the CPU_FAN header. Nothing horrible will occur should you use a special fan header—supplied the CPU fan nonetheless works if you flip the PC on—however you may get a warning that the CPU fan is not detected if you boot up your system. Utilizing a Y-splitter to attach two followers to the CPU_FAN header can also lead to a CPU fan warning.

After all, in case your CPU fan retains the CPU sufficiently cool, this is not a problem, and you may flip the warning off within the BIOS. Nonetheless, it is simpler to plug within the CPU fan within the appropriate header slightly than taking additional steps to bypass it.

CPU_OPT Is for a Second Cooler Fan

CPU_OPT (additionally CPU_FAN2, and so forth.) stands for “CPU Optionally available” and is a four-pin fan header for a secondary CPU fan discovered on massive air coolers. CPU_OPT has solely three pins on some cheaper motherboards, which suggests it will possibly lack PWM fan management. The CPU_OPT header is often positioned subsequent to or beneath the CPU_FAN header, so it is simple to combine up the 2, even for knowledgeable PC builders. If you happen to’re working a inventory CPU cooler or AIO, or your cooler solely has one fan, you possibly can ignore the CPU_OPT header.

The CPU_OPT header is beneficial when you’ve got an aftermarket cooler with two followers. Offered it has 4 pins, you may get the identical PWM performance as on the “main” CPU fan, and you need to use the identical fan curve for each followers to optimize cooling and decrease noise. Like CPU_FAN, CPU_OPT adjustments the fan pace based mostly on the CPU temperature.

You too can use CPU_OPT like every other fan header so as to add extra case followers to maximise airflow. You may join both a three-pin or four-pin fan to the CPU_OPT header, as they’re interchangeable. The header’s location is useful if you wish to add a fan on the prime of your case. A Y-splitter on the CPU_OPT header will not be a problem, supplied your motherboard can deal with the load.

You should utilize CPU_FAN or CPU_OPT for an AIO pump connector in case your motherboard lacks an AIO_PUMP (or W_PUMP) header. Nevertheless, in case your AIO pump requires PWM and also you solely have a 3-pin CPU_OPT header, this is not a good suggestion.

CyberPowerPC Grvty High Airflow Series gaming PC case's RGB fan and vents
Justin Duino / How-To Geek

What About SYS_FAN and CHA_FAN?

SYS_FAN stands for “system fan,” and CHA_FAN is “chassis fan.” SYS_FAN and CHA_FAN are primarily totally different names for a similar factor; they’re case fan headers unrelated to the CPU_FAN and CPU_OPT. They are often both three-pin or four-pin headers, and so they’re interchangeable. SYS_FAN is the older of the 2 names, as PCs historically had solely a single exhaust fan within the again.

You may join as many or as few case followers as you need, assuming your motherboard has sufficient headers for all of them. I like to recommend having at the least one exhaust fan to push sizzling air out of your pc, as having no case followers can lead to your pc overheating.


On the finish of the day, it would not actually matter the way you hook up the followers to the motherboard so long as you make it possible for the CPU fan pace follows the CPU temperature within the BIOS. It is best to hook up all the pieces “accurately” from the get-go to be able to spend much less time tinkering and extra time enjoying video games or working.



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