What Causes a Computer Fan to Make Noise?
A properly cooled system enhances both stability and performance in a computer. One of the main components for cooling is through case and component fans, yet most of the noise from the computer is generated by these fans. So why do they make so much noise?
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Noise From Normal Operation
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Fans make noise in normal operation. As the fan blades cut through the air, they disrupt the air, causing sound. Thus, the spinning fan results in a low humming noise. The noise of these fans becomes more noticeable in a computer because of its enclosed space. In addition, the computer has fans to cool the CPU, the case in general, the power supply and, at times, hard drives and video cards. Each fan contributes to the overall computer fan noise.
Noise From Type of Fan
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Fans come in either sleeve- or ball-bearing types. With a sleeve-bearing fan, the fan spins within a lubricated ring of material. As the lubricant wears down, the fan becomes louder until it eventually fails. With a ball-bearing fan, the axis of the fan glides along small steel balls to rotate.
Sleeve fans are quieter than ball bearing-fans until the sleeve material breaks down. However, ball-bearing fans tend to last longer than sleeve-bearing fans, resulting in a more consistent noise level.
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Noise From Obstruction
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A fan will make noise if there is an obstruction in the way of the blades, anything from built-up dust to loose wires. This is the easiest fan-noise problem to fix as it is simply a matter of removing the obstruction. Sometimes, the fan can be obstructed by its housing. This results when the fan becomes imbalanced and doesn't rotate uniformly.
Noise From Size and Speed
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In normal operation, bigger fans are louder than smaller fans because they move more air. Given the same airflow, though, a smaller fan would be louder. This also shows the relationship between speed and noise. As fans move faster, they generate more noise. Higher fan speed can result from elevated temperatures in the case because warm air moves faster than cold air.
Considerations
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Computer fan noise is inherent to normal operation. However, the type of case and the size of the room can contribute to how noticeable the fan noise is. Cases that have multiple exhaust fans and side vents produce more noise than cases without. Likewise, overall fan noise is more noticeable in a small room, compared to a wide-open large room. The right amount of computer fan noise is a balance between the noise and the desired amount of cooling for the system.
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