Quiet PC - Causes of Noise

Causes of Noise

The main causes of PC noise are:

• Mechanical friction noise generated by micro motors and fan bearings, as well as vibration noise from low quality chassis and improper assemblies.
• Turbulence caused by obstructions in the flow of air, such as poorly designed fan grilles and heatsinks. A lack of clearance between rotating fan blades and nearby support struts and grilles will create an audible noise, similar to how a mechanical siren operates. As the fan blades spin, they produce a vortex of air that trails off the edge of the blade. When the vortexes path crosses an object it may produce noise. Fan blades can be designed to reduce this problem by using special notched shapes.
• Noise generated by electrical coils or transformers used in power supplies, motherboards, video cards or LCD monitors.

Noise in personal computers has been increasing with rising computing power and number of transistors on a single die (integrated circuit). More transistors of a given size use more power, which releases more heat. Faster-rotating cooling fans are one common way to remove this heat. Also, the rotation speeds of hard disk drives and optical disc drives have increased. Higher rotation rates can increase vibration and bearing friction, thus creating more noise.

The noise issue had received widespread attention with AMD's early Athlon CPUs and Intel's Pentium 4 Prescott core CPU known for its excessive heat and bundled fan noise running on high RPM. With the introduction of Home Theatre PCs (HTPC), the excessive heat and noise problem, that had been mostly confined to the overclocking and quiet computing communities, came to the attention of the general public.

The main approaches to reducing noise problems from personal computers are:

1. Reduce heat generation by using energy efficient parts - nearly all the energy used by a computer is converted into heat.
2. Improve cooling - by using more efficient cooling parts and lower friction, quieter bearings.
3. Use soundproofing to reduce the effects of remaining noise sources.