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)
Shout (5 feet)
Heavy truck (50 feet)
Normal conversation (3 feet)
Bedroom at night
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.
So explaining sound is always difficult, but up-to 40 DBa is considered to be silent. Once you are in the 41~43 DBa range you can hear the product and after 44 DBa the product can be considered to be a noisy cooler.
We now put the processor under 100% load again with the processor under full load for a full Prime95 run. Noise pressure is a difficult thing to explain alright.
So if you want silence then up-to 39~40 Dba is your baseline threshold. The Kraken X40 even in silent mode can be heard a bit. Its performance however is outstanding as you are about to learn. Switching to Extreme performance mode brings a nasty tradoff, the Kraken X40 will become very loud.
Overall we recommend to stick to the silent operating mode as really, it only differs a few degrees C with the Extreme performance mode. But let me demonstrate that with an overclocking session.