Well, after nearly two months of virtual silence, the fan in my 12" iBook G4 finally made its presence known. Despite using the system for several hours each day, with room temperatures up to a very warm 30 degrees C, the fan had never increased to a speed that could be heard more than a metre a way in a very quiet room (indeed, you'd need to put your ear close to the keyboard to properly hear the soft air rushing sound). But after about an hour of running the Folding@Home client for the first time, with a room temperature of 27 C, the fan suddenly revved up, much to my surprise. It could probably be described as about half as loud as the optical drive at full spin. After about ten minutes, it still hadn't slowed, so I shut down Folding@Home. Within two minutes, it was back to virtual silence. The sudden relief this provided was a much needed reminder of the value of a quiet system design.