i don't think that cooling the heat pipes at point of contact with the chip is the most efficient way to use them unless they are double layer or more.
The way i see it is that the point of contact needs to get hot enough so convection can work properly as the liquid needs to heat up so it can turn to gas then take that energy to the cooling area to be wasted and become a liquid again then wick back down..
i do like to see heat pipes. but i don't like to see the efficiency of them diminished by cooling them at the point where they should be gathering the energy needed to work.
Personally i prefer to see double layer heat pipes. as this would allow the lower level to heat up properly to work, and the second layer would only start to work effectively if temperatures exceeded the point where the single layer was unable to cope.
if your directly cooling the heat pipe at the point of contact then you may as well have a big copper block with grooves cut in it to increase the surface area for the air, and just solder some fins to the side of that. im not saying that would not be effective. infact it would probably be a lot more effective than just cooling heat pipes at the point of contact. but then you lose the benefits of heat pipes, which is to be able to make efficient and effective heat sink which are smaller and lighter.
