Fan Noise

In 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.

While the idle fan noise is fine, the noise under load seems to be a bit high to me. When you compare the Zotac 9600 GT's fan noise to the GeForce 8800 GT - which has a higher heat output you realize that there is still some room for improvement left in Zotac's fan control. This does not mean that the card will be noisy - it is just louder than necessary in my opinion.

When the card was running under load our sample had a very loud coil noise present. Coil noise is caused by vibration inside one or more coils of the power conversion circuitry on the card. It is more or less random and can show on one card and not one the next one produced on the assembly line. I checked with other reviewers and they had not encountered this issue, I am listing it here for completeness. In my case I could fix it by routing the PCI-Express power cable in a different way so it would pull slightly on the PCB warping it a tiny little bit (nothing you could see).