Noise Level
The Radeon HD 4850 was extremely quiet at idle, but its big brother can’t boast quite the same performance – despite the change to a dual-slot fan, the Radeon HD 4870 tends to be a little less quiet at idle according to the sound-level meter, even if the difference is relatively slight in practice. At 1045 rpm – only 12% of its maximum rotation speed – its fan can still be considered quiet.
Under load, the trend was reversed. While the HD 4870 is clearly not as quiet as the Radeon HD 3870, it’s still tolerable overall (the fan ramps up to 1600 rpm), and a lot quieter than the very noisy GeForce GTX 260.