Do you also put the thermal paste on the pipes as well ?
The purpose of thermal paste is to fill in microscopic pits in the mating surfaces so that there is no air trapped. Air is a very poor heat conductor. The thermal paste is not a great conductor, either, but it is much better than air.
If you use too much paste, it will act as an insulator which is not good. You really want to use as little as possible.
For the heat pipe coolers like the hyper212, you sometimes get seams, so filling them with paste is better than leaving them filled with air. It is the contact with the pipes themselves that is most important, and you want to use very little paste there.
If you put a small drop in the middle, pressure and heat will make it flow outward and avoid air pockets.
To satisfy yourself on how this works, plan on seating the cooler twice.
After you do it the first time, and have heated up the cpu, take the cooler off and see how the paste has spread. See if you have not used enough, or, more likely, you have used too much. Then clean it all off and make whatever adjustment you need to.