be quiet Pure Loop 2 FX 280mm LCS review

Cooling 193 Page 7 of 9 Published by


Noise levels - Sound pressure readings

Acoustic Performance

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.

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 




In idle, you hardly hear the fans. Once we put the processor at 100% load with several full wPrime runs. Noise pressure is not an issue at default. 


So that makes one wonder; what happens when we overclock? Well, DBa levels rise to a very audible level only once we pass 1.30-1.35V voltage to the processor and overclock. Of course, you have the freedom to tweak FAN RPM behavior to your liking at the cost of performance.

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