At its lowest setting the cooler is very quiet: 31.8 dB(A) is nearly inaudible, depending on room noise levels. At full blast, however, the noise volume reaches 38.7 dB(A), a level that most people would find annoying.
At full power the temperature rises to 56 °C for the copper model. When the speed is reduced, the temperature rises to 64 °C, but the CPU still doesn't throttle. The figures for the copper/aluminum version are somewhat poorer: the temperature reaches 63 °C when the fan is rotating at maximum speed, but when the fan is turned down to a slower setting, the temperature rises to 72 °C, and the Pentium 4 580 begins to throttle.
In the essential trade-off between cooling capacity and noise production, this cooler is right in the middle: the CPU temperature is fine, and the noise made by the cooler is not bothersome.
The thermal resistance ranges from 0.25 K/W for the all-copper model at the highest speed setting (which is very good), to 0.33 K/W for the copper/aluminum variety at the lowest setting (which is not so good).
The copper cooler costs $43, while the aluminum-copper model sells for slightly less $35. Since the price difference is minimal while the differential in cooling capacity is significant, we recommend the copper model.