EK Fluid Gaming A240G CPU & GPU Liquid Cooling review

Cooling 189 Page 13 of 16 Published by

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Noise levels - Sound Pressure Readings

Noise Levels

With a certified dBA meter we measure how many dBAs originate from the PC. It's slightly subjective as there is always noise in the background, from the streets, from the HD, PSU fan, etc so this is by a mile or two not a precise measurement. You could only achieve objective measurement in a sound test chamber. Take this measurement as an indication, not a precise measurement please.

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBA level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement. Frequencies below 1kHz and above 6kHz are attenuated, whereas frequencies between 1kHz and 6kHz are amplified by the A weighting.

TYPICAL SOUND LEVELS
Jet takeoff (200 feet) 120 dBA  
Construction Site 110 dBA  Intolerable
Shout (5 feet) 100 dBA  
Heavy truck (50 feet)  90 dBA  Very noisy
Urban street  80 dBA  
Automobile interior  70 dBA  Noisy
Normal conversation (3 feet)  60 dBA  
Office, classroom  50 dBA  Moderate
Living room  40 dBA  
Bedroom at night  30 dBA  Quiet
Broadcast studio  20 dBA  
Rustling leaves  10 dBA  Barely audible 

But let's have a peek at noise levels. We take a dBA gun and point it at the working PC and take a distance of 75 CM.

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Explaining sound (or noise levels) is very difficult, but up-to 40 dBA is considered to be silent. Once you're in the 41~42 dBA range you can hear the product and after 43~44 dBA the product can be considered to be a moderately noisy cooler. Any number after that is unacceptable for cooling. In default conduitions this unit is silent. 

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There's another side to the story though. What if you overclock and this need to draw more heat? Well once you start to overclock the dBa pressure starts to rise. With a normal overclock up-to say 1.30 Volts and a Core i7 4790K processor the dBA levels remain silent enough. Once you pass after 1.35 Volts do we reach higher, audible dBA levels. At 1.40 Volts the cooler becomes too noisy for our taste.

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