Introduction
Did you know that you can modify any fan located inside your PC – CPU fan, VGA fan, north bridge fan, case fan, etc – to run at three different speed levels (low, medium and high) without spending any money at all? This is possible by just changing the configuration of the wires used by the fan. In this tutorial we will give you detailed instructions on how to do that, reducing the noise produced by your PC.
Fans can have two, three or four wires. Below you have a breakdown of the function of each pin and the most common color for the wire attached to that pin. There are two important things to notice here. First the color of the wires may change depending on the fan manufacturer. These are just the most common ones. Second, all fans are fed with+12 V; however several fans use a red wire on their +12 V line, being different from the color code used by the power supply, where red means +5 V.
Pin | Function | Wire Color |
1 | Ground | Black |
2 | +12 V | Red or yellow |
3 | Fan Speed Sensor | Yellow, white or green |
4 | PWM Control | Blue |
Also notice that during this tutorial our examples will be with a CPU fan, but everything we say is valid for any kind of fan located inside the PC: video card fan, chipset fan, case fan, etc.
On Figures 1 and 2 you can see a three- and a four-pin connector, respectively. Notice that the counting is done with the key present on the connector up.
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Figure 1: Connector from a CPU fan using three pins.
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Figure 2: Connector from a CPU fan using four pins.
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Figure 3: CPU fan connector on a motherboard. You can install either three- or four-pin fan connectors here.
The first two pins supply the voltage required for the fan to spin. The third pin is connected to the fan speed sensor, reporting to the motherboard the current fan speed. This value can be read at the motherboard setup (see Figure 4) or thru a monitoring program, such as Motherboard Monitor. And finally the fourth pin is a speed control input, also known as PWM (Pulse Width Modulation) control, provided by the motherboard. On fans that have this fourth pin the motherboard (or video card) can control the speed of the fan, usually automatically depending on the CPU or GPU (graphics chip) load.
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Figure 4: Motherboard setup.
If your fan has four wires, you don’t need to do what we will teach in this tutorial, as you fan has already a speed control circuit. Just go to the motherboard setup and look an option to enable this feature (“CPU Smart FAN Control” and setting mode to “Auto” on Figure 4). This will reduce the CPU fan speed automatically when your computer is idle or when you are not using a heavy application like playing a game.
If, however, you are not satisfied with the PWM control provided by your computer, you can remove the fourth pin (see how on Figures 6 and 7) and execute the procedures described on this tutorial.
Reducing the fan speed is just a matter of feeding it with a lower voltage. But how can we do that if the fan connector only provides +12 V? That is exactly the trick we will teach you: we will remove the fan power wires from the fan connector and install them directly to one of the peripheral power plugs from the power supply. This way we will be able to feed the fan with +5 V (low speed), +7 V (medium speed) and + 12 V (full speed). Read on.
Removing the Pins from the Connector
The first thing we need to do is to remove the power wires from the fan connector, i.e. the first and the second wires.
If there is a sleeving protecting the wires, you will need to open it with a blade or scissors, as shown on Figure 5. Later you will need to cut the portion of the sleeve that will be hanging with a scissors.
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Figure 5: You will need to open the sleeving if your fan has one.
To remove the pins you will need a precision screwdriver (here we used a 1.4 mm one). Look carefully to the fan connector and you will see a small opening in front of each pin. Thru this opening you can reach the lock that holds each pin in place. What we need to do is push this lock with the screwdriver in order to release each pin, like shown on Figure 6. Then just pull gently the wire and it will come out of the connector, like shown on Figure 7.
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Figure 6: To remove a pin from the connector, push its lock with a precision screwdriver.
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Figure 7: Then pull the wire gently.
The third wire must be kept on the connector and you will install the connector back to the motherboard, as shown on Figure 9. If you are modding a fan with 4-pin connector, the fourth pin should be also removed and insulated with insulating tape.
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Figure 8: Our connector after we removed the two power pins.
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Figure 9: Connector installed back on the motherboard.
Now it is time to connect the pins to the power supply.
Connecting the Wires to the Power Supply
Now you will connect the wires from the fan to any unused peripheral power plug from the power supply. The way you will connect the fan wires to the power supply will depend on the speed you want to configure your fan with. You have three options: low speed (+5 V), medium speed (+7 V) or full speed (+12 V). You may be asking yourself how can we get +7 V since the power supply doesn’t provide such voltage. Here is the trick. If you connect one wire to +12 V and the other wire to +5 V you will have +7 V (12 V – 5 V = 7 V). It works like a charm.
So for low speed you will connect the black wire from the fan to the power supply black wire and the red (or yellow) wire from the fan to the red wire from the power supply. As mentioned this will provide +5 V to the fan. We show how this is done on Figure 10.
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Figure 10: Installation for low speed.
For medium speed you will connect the black wire from the fan to the red wire from the power supply, and the red (or yellow) wire from the fan to the yellow wire from the power supply. As mentioned this will provide +7 V to the fan.
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Figure 11: Installation for medium speed.
And for full speed you have two options, one is to install the fan wires back to the fan connector or to connect the black wire from the fan to the black wire from the power supply and the red (or yellow) wire from the fan to the yellow wire from the power supply.
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Figure 12: Installation for full speed.
Originally at http://www.hardwaresecrets.com/article/496
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