Originally posted by: ActuaryTm
Actually, by very definition, a heatsink is merely any device that aids in dissipating heat away from a given source - regardless of the material of said source. In this case, the conductivity of plastic (thermal constant < 1) is indeed not wonderful for the transfer of heat; however, as most know, aluminum's thermal conductivity is quite acceptable (thermal constant ~200). Even without the fans nor a true "bond" between the two materials, the ample aluminum surface area (in addition to the ventilation under the aluminum) would allow for quite a bit of heat to be absorbed and then dissipated. The fans only help this.
It's shear physics, very plain and simple.
I knew where this was going once I saw the "actually, by very definition." Yah, a pencil touching the side of a laptop is a heatsink too.
You then might be interested in some innovative new supplemental CPU heatsinks I'm developing. They don't actually touch the CPU, and they're encased in plastic, but the metal within is copper. And look at the thermal conductivity of copper...400! Wow, a must have for any computer system. Guaranteed to feel warm to the touch next to any hot CPU.
These coolers do help and this is a competitive price for one - I just found their marketing too much like any of the other gimmick products out there. The air circulation (c/o the fans) under the laptop is doing the cooling work. Any heat dissipation done by the aluminum base through an air gap, a layer of plastic, and another air gap (along with the plastic/rubber feet on the cooler) is going to be negligible in lowering the internal temperature of your laptop.
But hey, if you need a laptop cooler, might as well get one that's aluminum, especially when it's cheaper than the plastic ones.