The 4-pin CPU_OPT (CPU Optional) port on a motherboard is where CPU fans can be plugged in. If your CPU fan has two different headers, you can plug the main one into your CPU_FAN header and the other one into your CPU_OPT header.
If there are more than two headers, you can use a splitter to join them so that you only need one cable to connect the secondary headers to the CPU_OPT header.
Your system should be able to start up without anything plugged into CPU_OPT. Its primary purpose is to connect cooling systems with multiple fans or to run AIO cooling pumps when you can’t use the AIO_PUMP header on the motherboard.
Just be aware that if you plug the AIO pump into CPU_OPT, you won’t be able to change its speed in the BIOS.
What is CPU_FAN?
The central place to plug your CPU cooler’s fan into a motherboard is the 4-pin CPU_FAN port, usually near the CPU socket. This CPU_FAN header should be set as the main one for cooling the CPU on your system.
If there’s no fan connected to the CPU_FAN header, your motherboard will probably think there’s no fan cooling your CPU and won’t let you boot the machine.
Because of this, you must make sure that the CPU fan is connected to the CPU_FAN port. This lets the system know that the CPU is being cooled, and you can control the CPU’s temperature by changing the CPU fan’s speed in the BIOS.
What is a CPU FAN header?
The main header on a motherboard is the CPU_FAN header, as shown on your motherboard.
The CPU FAN port is where your motherboard wants you to connect your CPU fan, as the name suggests. Even so, this rule is insignificant. It would help if you still plugged in your CPU fan, but you don’t have to do it there.
The only difference between the CPU fan header and the other fan headers is that the CPU fan has built-in safety to protect your CPU from damage. The computer won’t start if you don’t plug a fan into the CPU fan header. Instead, after POST, your PC will give you a warning message that says something like this:
“CPU fan error!”
Also, if your PC is already on and you accidentally or on purpose cut the link to the CPU fan header, the PC will shut down.
Almost all CPU FAN headers are 4-pin, meaning the BIOS, OS, or PC software suite can control the fan’s speed. This means that the computer has complete control over the fan and can quickly speed it up when it senses that the CPU is getting too hot.
Do you really need to use the CPU fan header?
Yes, of course, you have to connect your CPU fan to a fan header. If you don’t, your CPU will melt in its socket. But the longer answer is no. This “CPU fan error” feature can be turned off in the BIOS, and you can use any fan header you want. However, some things could be improved with this.
As we’ve already said, there are some excellent reasons to use the CPU fan port. Real-time temperature data is sent to the system to change the fan’s speed instantly.
This means that you get better cooling right when you need it. Have you ever noticed that it gets louder as your PC gets hotter? You can thank this feature for that.
CPU Fan Header Locations
The CPU_FAN and CPU_OPT lines should be close to where the CPU socket is on your motherboard. They are usually next to each other, up and to the CPU’s right, near the RAM’s DIMM slots. “CPU_FAN” and “CPU_OPT” should be written next to these ports on your motherboard.
Their places can be different, though, based on the motherboard. If you can’t find the headers, look at the diagram in the instructions for your motherboard. It should show where they are.
Can You Use CPU_OPT for Case Fans?
You can use the CPU_OPT header to control case fans, but it’s not advised when you can use the SYS_FAN or CHA_FAN headers instead. Like CPU_FAN, CPU_OPT is only linked to the CPU’s temperature sensor. This means it is not linked to the temperature of the whole system or other parts.
So, if you connect a case fan to the CPU_OPT line, you won’t be able to control its speed based on the temperature of the whole system. Instead, it will only be controlled by the temperature of the CPU.
But if your system has no more SYS_FAN or CHA_FAN headers and you need to plug in another case fan, you can use CPU_OPT.
CPU_OPT vs CPU_FAN
Both the CPU_OPT and CPU_FAN headers can be used for CPU fans, but only the CPU_OPT header is “optional,” as its name suggests. If you don’t plug a fan into the CPU_FAN header, your computer will probably think there’s no fan cooling the CPU and won’t let you start up.
CPU_OPT should be used for extra CPU cooling connectors, like those found in a radiator with more than one fan. It can also be used for an AIO pump if you can’t connect it to the correct AIO_PUMP header. However, if you do this, you won’t be able to set the speed of the pump from the BIOS.
Lastly, you can plug case fans into CPU_OPT if there are no SYS_FAN or CHA_FAN lines. However, the speed of these fans will only change based on the temperature of the CPU, not the temperature of the whole system.
What Are CHA_FAN & SYS_FAN Headers?
CHA_FAN, also known as the Chassis fan header, is a header that allows the chassis fan to be plugged in. A fan that is attached to the exterior of the PC case is referred to as the chassis fan. It can be mounted either on the outside or on the inside.
From the motherboard, this pin connector is headed toward the case fan. The CHA_FAN can have either a 3-pin or 4-pin style. The design with three pins is conventional. However, the connector with four pins offers improved speed and better cooling.
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System fans are what the SYS-FAN title is for. The speed of these fans depends on how hot the CPU is. Also, the SYS_FAN header lets you set a specific speed for the system fans.
The SYS FAN joins the system fan inside the CPU and helps the fan channel cool air inside while sending hot air outside. Use a base and system fan if you have a high-end graphics card. These two will keep your device cool and ensure the air flows correctly.
Conclusion
As was previously said, it is highly recommended that you check to see that your CPU cooler is connected to the CPU_FAN header.
The remaining fans and power cables can be connected to the CPU_OPT header, either with a single connecting cable or via a splitter that will enable multiple fans to be powered via the CPU_OPT.
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In addition, if your CPU cooler has several fans that need to be powered by several different headers, the remaining fans and power cables can be connected to the CPU_OPT header.
FAQs
Should I use CPU opt?
The central processing unit (CPU) always stays cool thanks to a unique connection on the motherboard called CPU OPT. Therefore, it is recommended to just use CPU OPT for the fans. If you connect the AIO Cooler to the CPU OPT port, you need to make sure that the radiator is also linked to the CPU FAN port.
What does CPU opt mean?
What exactly is the CPU OPT (CPU_OPT) setting? CPU_OPT, which stands for “CPU Optional,” is primarily utilized when you need somewhere to connect in additional fans on your cooler or radiator. This is typically the case when you have more than one fan on each component. In practice, it is the same as CPU_FAN, although it does not prevent booting if there is no device connected to it.
What is CPU opt and CPU fan?
You need to look at the “CPU_OPT” variable if your computer has more than one fan to cool the CPU. It is a supplementary header that will connect the other fan. The abbreviation “OPT” refers to the word “Optional.” Therefore, the cooling fan that is optionally used is the fan that is attached to this header.
Can I plug a fan in CPU opt?
You certainly can; in fact, I’m currently operating my computer with a fan connected to each of the headers. In spite of the fact that the manual labels them for different purposes, the CPU_FAN and CPU_OPT headers are, in practice, the same thing: they are PWM headers.
Does high CPU usage damage?
It is normal for high-intensity games and apps to reach the boundaries of the CPU, and this typically does not have a negative impact on the overall performance of the system. On the other hand, if an abnormally high percentage of the CPU is being used, the computer may stutter, stop responding, or even crash.
