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. The 3D load noise levels are tested with a stressful game, not Furmark.
In idle, AMD's Radeon HD 6990 emits reasonable noise levels considering all the performance you have available at the click of a button. With 34 dbA the card is noisy though, when compared to other cards on the market.
Under load all the power the card consumes is turned into heat which means the fan has to work extra hard to get rid of the heat to keep the GPUs cool. As a result the card is really, really noisy. Think of a table fan that keeps you cool in the summer, that should give you a rough idea of the noise levels to expect.