T. Random (May 02, 2001 02:51 p.m.):
I'm not trying to deny facts: the sink with the hollow core appears to indeed work better. I'm questioning the physics of the effect. My best guess is that the something else than just the structure of the core must have changed in the Thermoengine to explain the results. Maybe they changed also the material when they changed the tooling method. Just guessing...
The moral of the story: Don't drill your solid-core Thermoengines. You'll end up with an even worse sink.
I disagree with you. Heat is evacuated from the Thermoengine by cooler air passing by the radial fins (pushed by a fan).
Thermal energy moves from an area of greater energy to an area of lesser energy towards a state of equilibrium. If we assume that the CPU is always hotter than the heat sink (easy assumption), then we can expect the heat to travel from the cpu to the bottom of the sink. From there, it moves from the bottom of the sink throughout the sink, eventually being exported via cool air flow at the fins.
If you compare a Thermoengine that is hollow versus a thermal engine that is solid, the following will be true: the same amount of heat energy will have less heatsink volume in which to accumulate. Therefore, the hollow sink, given the same input energy, will be hotter at the fins than a solid one, because a solid one has more volume to "soak up the heat". However, the only place where there is active export of heat is at the fins. The more heat that is transferred to the fins, the more effective the sink is at exporting heat.
The hollow core does not magically "pipe" heat away. Calling it a heat pipe is a serious misnomer. However, air is very poor at holding heat. A vaccuum is incapable of holding heat. The hollow chamber's main point is merely to NOT HOLD HEAT.
An ideal fansink would:
A) maximize contact area with the cpu (limited by cpu size in most modern sinks, and aided by thermal paste such as arctic silver)
B) Have as high an export area to heat holding volume ratio as possible. (fanned fin area/volume).
C) Push as much air volume across the export area as possible.
A hollow thermoengine is more ideal because of point B, and therefore, should be more efficient.
Neil
