The ICE cooling system takes up quite a bit of space by itself. This is mostly due to the fact that Shuttle has designed it for maximum airflow. On one side is the intake fan which pulls air in from the outside and via a shroud on the opposite side, funnels it right back outside the case after it moves across the radiator fins of the heatpipe.
The cooling system consists of three components, the intake fan, the heatpipe itself and the shroud which directs the airflow. On the heatpipe is another fan, just smaller. Shuttle takes their cooling seriously as this brings the fan count up to a total of five. For such a small unit, this is quite a lot.