In acoustics, the decibel is used as an absolute indicator of sound power per unit area. Abbreviated as "dB", this measurement is defined as the power per unit surface area. To give you an idea of scale, 0dB is the threshold of human hearing and 120-140dB is the threshold of pain.

For the purpose of CPU coolers, case fans, hard drive coolers etc, many users have noted that the actual decibel specification of the device has limited correlation to the physical noise produced by a fan - this has to do with standards in measurement and also due to how fans generate noise in the first place.

Fan noise can be attributed to:

• the movement of physical parts
  
• the vibration of whatever the fan is mounted on (such as a plastic mounting bracket as in the case of Antec, or just directly onto the case panels)
  
• the space around the fan
  

Depending on the manufacturer, the fan noise measurement may be so different that you can NOT rely on measurements supplied from a manufacturer to compare potential noise from products by different manufacturers. The only REAL way to know the difference is to set up a controlled environment to measure the fans. However... you can generally use the decibel measurements to compare fan noise of products from the SAME manufacturer. For instance if you already know that one fan from a manufacturer is rated at 36dB and the other fan is rated at 50dB then you can sort of estimate the relative noise of the coolers.

Because decibels are a logarithmic scale, human perception deems that an increase of 10dB is about double the volume.

Below is a chart we made to show you visually some real world noise in decibel levels. (note that the chart is not to scale... the upper decibel ranges are more widely spaced to emphasize the fact that at the upper ranges even small decibel changes would result in a very large perceptive noise change).



The sound level in the average residential home or in a quiet conversation is about 40 dB. Average conversation volume is about 60 dB, and typical home music listening levels are about 80-85 dB. Those live band performances? About 110 dB, and a jet engine close up is well into the pain threshold. For the purpose of coolers, active cooling can range from 20db to the higher 60dB range. The lower 20dB range is very very rare for active cooling, since water cooling is also around that range.

As a general guideline, a good typical range for coolers is 26-40dB for relatively quiet cooling. Remember though that manufacturer specs CANNOT properly give you an absolute idea of the noise that the fan will make.

Did you know?
A decibel is one-tenth of a Bel, a unit named for Alexander Graham Bell, inventor of the telephone. The Bel is rarely, if ever used anymore.

Is this answer useful? Yes   No So far 432 of 596 person(s) think this answer is useful.