During POST (Power-On Self Test) test, your motherboard makes sure that all major hardware components are connected and in a working state. This includes the CPU fan as well.
CPU fan is what cools down the CPU chip when its temperature rises. The heat is transferred to the heat sink. CPU fans then cool the heat sink. And this is basically how a CPU cooler works.
If you do not place the CPU fan header to the correct pins on the motherboard, the fan may not spin at all or will spin at a lower RPM. If that happens, there is nothing to cool down the heat sink. This is when you face thermal throttling. Meaning that the CPU will lose its performance.
Today, to avoid this exact issue, we are here to provide you with a detailed and simple guide to connecting the CPU fans header to the motherboard.
Does It Matter Where I Plug My CPU Fan?
If nothing is connected to the CPU_FAN header on the motherboard, it will display some errors during the POST test. If the computer passes the POST test, the CPU fan might spin as long as it is connected to the SYS_FAN header. However, it will spin at its maximum RPM, making a lot of noise.
Besides this, the voltage supplied to the CPU_FAN header on the motherboard is temperature-controlled. Meaning that depending on the temperature, the system increases or decreases the temperature. You will not have this feature if you connect the CPU fan to a different header.
How to Connect CPU Fans Header to the Motherboard?
Inserting the CPU fan connector into the motherboard is a simple task if you know where the headers are located on the motherboard. You need to connect the cable from the CPU fan to the header named CPU_FAN on your motherboard.
First, let us see where this specific header is located.
Locate CPU_FAN Header On Motherboard
As you have already noticed, the wire from the CPU fan is relatively short. Therefore, the CPU_FAN header is also located near the CPU socket on the motherboard.
To locate them, search for the four-pin header on your motherboard. You might see multiple four-pin headers. Make sure that CPU_FAN or CPU_OPT is written under it. There may be a single or multiple CPU_FAN on your motherboard.
If it has multiple CPU_FAN headers, it is indicated as CPU_FAN1, CPU_FAN2, etc. Make sure that you do not connect to the header named SYS_FAN.
Insert the Cable From the CPU Fan
Once you locate the CPU_FAN header, take the wire from the CPU fan. Align the cable and the header and gently connect. This cable only goes in one way. So, do not force them in if you cannot insert them. Flip the cable and try again.
After connecting the CPU fan to the motherboard, turn on the computer to check if the fans spin. If you have the motherboard connected to the monitor, check if you see any errors regarding the CPU fan during the POST test.
Is My CPU Fan Compatible With Any Motherboard?
CPU fans generally have a four-pin connector, and most motherboards also come with a four-pin header. So most CPU fans are compatible with any motherboard. However, the case is not the same for the CPU case fan.
CPU case fans either have Molex, three-pin, or four-pin PWM connectors. Therefore, your motherboard must have the fan’s respective header for connection. You might need to get a converter if it does not have the required headers.
How to Connect System Fan on the Motherboard?
Depending on the type of fan, you can either connect the CPU case fan or the system fan directly to the motherboard or the power supply.
If you have a 3-pin or a 4-pin cable from the case fan, you can directly connect them to the motherboard. However, if the case fan has a Molex connector, you need to connect it to one of the cables from the power supply.
The 3-pin and the 4-pin cable go in the header named SYS_FAN on your motherboard. Although SYS_FAN has a total of four pins, you can connect it to a 3-pin connector as well.
How to Control CPU Fan Speed?
You can either use the BIOS or some third-party application to control your CPU fan speed. BIOS offers convenient ways to control CPU fan speed, but having a third-party application makes it a lot easier to control CPU fans and system fans.
If you want to control the CPU fan using the BIOS, follow the steps mentioned below.
- Press the BIOS key repeatedly during startup to enter your motherboard’s BIOS. The BIOS key for your system can either be one of the function keys or the Delete key.
- Now, search for settings like Cooling, Hardware, or Hardware Monitor.
- Depending on the motherboard, you can either fully control the fan speed or set a certain fan control mode.
- Once you change these settings, Save and Exit the BIOS.
Why Is My CPU Fan Not Spinning?
The first thing you want to check when the CPU fan does not spin is the wire from the CPU fan. Make sure that you check the cable from the CPU fan is connected to CPU_FAN header on the motherboard.
Secondly, the PSU also needs to supply enough power to the entire system. If you have a CPU fan that is not spinning, try using a different PSU with a higher voltage.
Why Is My CPU Fan So Loud?
CPU fans generally spin at a higher RPM when the CPU reaches a high temperature. Therefore, checking the CPU usage should be your first priority when you have a CPU fan that is noisy.
Besides this, here are a few things you can try to lower CPU fan usage.
- End background processes
- Clean CPU heat sink
- Poor case airflow
- Make sure the cable from the CPU fan is connected to CPU_FAN header on the motherboard