Fan NoiseIn the past years users would accept everything just to get more performance. Nowadays this has changed with people being more aware of the fan noise and power consumption of their graphic cards.
In order to properly test the fan noise a card emits we are using a Bruel & Kjaer 2236 sound level meter (~$4,000) which has the measurement range and accuracy we are looking for.
The tested graphics card is installed in a system that is completely passively cooled. That is passive PSU, passive CPU cooler, passive cooling on the motherboard and Solid-State HDD.
This setup allows us to eliminate secondary noise sources and test only the video card. To be more compliant with standards like DIN 45635 (we are not claiming to be fully DIN 45635 certified) the measurement is conducted at 100 cm distance and 160 cm over the floor. The ambient background noise level in the room is well below 20 dbA for all measurements. Please note that the dbA scale is not linear, it is logarithmic. 40 dbA is not twice as loud as 20 dbA. A 3 dbA increase results in double the sound pressure. The human hearing is a bit different and it is generally accepted that a 10 dbA increase doubles the perceived sound level.
It looks like Powercolor struck gold with their selection of the Zerotherm cooler. Under idle the card is extremely quiet - quieter than what our (really good) sound level meter can measure. I am absolutely certain that you will not hear this card over your other components in the PC - even with the case side open.
Under load the card gets slightly quieter because it has to keep the card cool, but still it is the quietest card under load that we ever tested, with the exception of fan less cards of course. I honestly would not have believe that such noise levels are possible with the HD 4850 design.