Place a very small blob of thermal grease (mine might be a little too much) on the CPU and GPU only. Do not place any on the heat exchanger as well. You only need to place thermal grease on one or the other. Use the wooden depressor, plastic knife or old credit card to spread it evenly and very thinly over the surface of the area of the CPU / GPU or heat exchanger that will come in contact with each other. More is not better in this case. Too much thermal grease will not cause better heat conduction but might even cause some heat build up.