The ACA1240/1260 is taking shape: Our internal prototypes have been equipped with all custom-made parts of the cooling system for the first time this week.
The heat sink will replace the trapdoor cover of the A1200. On the final version, a rubber foot will make sure that the fan will always take in enough air that is blown against the fins of the heat sink.
The fan has been custom-made for us, and it's state-of-the-art: Speed can be controlled, and the current speed can be sensed (PWM and tach signals). This ensures that the required amount of air is available without generating unnecessarily high noise levels.
A high-precision temperature sensor is mounted in the heat sink. Especially the 68040, which does not have an integrated temperature sensor like the 68060 does, profits from well-regulated cooling: In power saving mode with 4.8V core voltage and 20MHz speed, the fan can always run almost without noise at lowest speed. Full overclocking with a core voltage of up to 5.5V is only allowed while the heat sink temperature stays within the specified range.