Sapphire HD 4850 Toxic 512 MB Review 14

Sapphire HD 4850 Toxic 512 MB Review

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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.

Sapphire has chosen to remove the temperature based fan control mechanism from their cooling solution. The fan will always run at the same speed, no matter if you run an idle system in Antarctica or under full load in the middle of the Saudi Desert. When asked, Sapphire replied that they "noticed that on many systems the problem is that the fan always starts and stops - at different temperatures. So we decided to always run at the same quiet fan speed".

This approach results in one of the noisiest cards under idle. When compared to the reference design HD 4850 the fan is 16.4 dbA noisier in idle - that's over 40x the sound pressure. Under load the margin gets smaller, yet the card cannot compare to the reference design when it comes to fan noise. However, the increased fan speed results in much lower temperatures and higher overclocking potential. Unfortunately power users won't be able to adjust the fan via any software. No matter what fan speed the card wants to run at the fan will always be around 1700 RPM.

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