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. The PC again is stressed at 3300 MHz on the CPU with 80% RPM set in the BIOS. These, as such, are noise levels measured under heavy CPU load.
On average and with a PWM regulated motherboard controller the cooler will run at roughly 65% RPM. In performance mode with 80% RPM we find the cooler too noisy at 43 DBa.
In silent mode the cooler definitely is not silent at 41 DBA / =<1500 RPM, but it remains an acceptable noise level to work in though.
Zalman CNPS 9900 DF review We review the Zalman CNPS 9900 DF CPU cooler with Dual Fan. It's 2012 and Zalman is going strong on the concept and just when you think they can't change anything on that design ...
Zalman CNPS 12X review The one that everybody remembers and still is going strong where the initial CNPS (Computer Noise Prevention System) CPU cooler, the copper somewhat rounded "butterfly" based coolers. That model has been the biggest success of all their coolers. Anno 2011 Zalman is still going strong on the concept and just when you think they can't change anything on that design they proof that a top notch new cooler based off that old design can still work out well and look gorgeous. The Zalman CNPS 12X comes with Zalmans heat transfer solution by utilizing composite heatpipe technology allowing a Q-Max of roughly 300W, along with a bigger design Zalman claims this cooler to be offering quiet operation and broad compatibility for Intel 2011/1156/1155/1366/775 & AMD AM3+/AM3/AM2+/AM2.
Zalman CNPS 10X Quiet and Extreme review Zalman recently released a new series of CNPS (Computer Noise Prevention System ) heatpipe based coolers. The new 10X coolers include five nice big heatpipes being cooled by a grotesque120mm fan. The PWM Fan comes with RPM Control which allows you to fine tune the cooler to your specific cooling requirements. And all that in a nice design and not too huge (in dimension) sized cooler. We will put two out of the three to the test namely the CNPS10X Extreme and CNPS10X Quiet. Both coolers impressed us a lot.