PWM cable is a small cable (wire) that is used inside the CPU. This is primarily used to connect your system fans to the motherboard. We will discuss in detail the PWM cables, how to connect them to a motherboard and its other end to a system fan, and why it is called a PWM cable.
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What is PWM:
Pulse width modulation refers to lowering the standard and destined power flow by an electric current or signal. This is done by dividing the electric signals into various parts. It helps in governing the average fed voltage into its load. The wire or cable that does PWM is used in multiple devices, which needs alteration in the speed and flow. Today we will discuss the PWM cable for system fans.
Where is PWM cable used:
This black-colored cable is applied to decreasing the current flow for fans mostly. These fans and PWM cable can be used for various devices and types of equipment like:
- Ductless air conditioners.
- Cooling laptops and desktop computers.
- For automobile ventilation systems.
- Photocopiers.
Connect PWM cable to system fan & motherboard:
If you open your CPU to attach a new system fan, or while building your CPU, you will be puzzled about which pin should be connected to your PMW cable’s end. You can use the manual if provided along with the CPU, or you can fetch the words “SYS_FAN” or “CHA_FAN” labeled on the motherboard. You can also use the below image as a reference:
Types of cables used for system fans (cha fan):
There are two different types of cables (wires) that can be used to connect your fans to the motherboard. They are:
Three pin cables:
These cables have only three pins on them. They can be connected to a motherboard’s sys_fan, whether they have three or four pins on them. The usage of those three pins are for:
Ground connection – Black layer
Voltage supply (12 Volts) – Yellow layer
RPM signal (Tachometer) – Green layer
Four pin cables (PWM):
Ground connection – Black layer
Voltage supply (12 Volts) – Yellow layer
RPM signal (Tachometer) – Green layer
PWM signal supply – blue layer
What is PWM Signal Cable Used for:
This cable is for establishing an uninterrupted connection between the PWM interface and some electronic devices like LED lights and core fans. It has an average length of 2 meters.
Is PWM cable important?
By using regular 3-pin cables, which are non-PWM cables, the motherboard won’t be able to alter the fan’s speed automatically, and every time you have to do it manually by installing software. This is widely used for case fans.
But the fourth wire of PWM cables helps alter the speed automatically, without the user’s intervention. This is more beneficial than a three pined one for the CPU fan and GPU fan. Both can be powered from the motherboard or directly through the PSU box.
Without using these cables and fans, the temperature of the core CPU and PCU will keep increasing and will either shut down your system automatically or burn down your system when the threshold temp value is crossed. There is a sensor placed near the core processor to note the temperature.
Where Can I Buy it:
The below are the top three best manufacturers of the PWM cable with the links to buy it:
Skineat
Ratings: 4.7 /5.0 (187 counts)
ThreeBulls:
Ratings: 4.7 /5.0 (1334 counts)
JbTek:
Ratings: 4.7 /5.0 (8500 counts)
PWM Y-splitter Cable:
This is also known as one to two splitter and connects two fans to the same motherboard port.
FAQs on PWM Cable
What is a PWM wire or PWM cable?
It is a cable to join the case fan and power fan to the motherboard to get a continuous power supply.
Is a PWM fan better or a DC fan?
PWM fans are power efficient and generate less noise. So PWM fans are better than DC fans.
Can a 4-pin PWM cable be inserted in a 3-pin motherboard?
Yes, you can insert a 4-pin cable into a 3-pin motherboard or a 3-pin cable into a 4-pin motherboard. The fan will still work correctly at full speed, even though the rate won’t be controlled.
Where should I plug the PWM cable?
One end should be attached to the system fan, while the other should be connected to the motherboard. On the motherboard, there will be PWM headers labeled as “SYS_FAN” or “CHA_FAN.” There will be four pins on it. This is where you need to attach the other end of the PWM cable.
Winding Up
Even though the weight and size of PWM cables are nothing compared to the whole system, the system gets wholly damaged when these are not installed and not given any notice. It is essential to keep an eye on the working of the system fan and the temperature of the core.
