be quiet! Pure Rock 2 review - 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 analysis in a sound test chamber. Take this measurement as an indication, not an exact 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 regarding 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 the A-weighting amplifies frequencies between 1kHz and 6kHz.

In idle, you cannot hear the fans. Once we put the processor at 100% load spread out over several full wPrime runs. Noise pressure is simply put not even a slight issue. 

So that makes one wonder; what happens when we overclock? Well, DBa levels rise once we pass 1.30V voltage to the processor and overclock. The product simply remains to be very silent.