PS4 GDDR5 RAM, Thermal paste instead of pads

NVM I found the answer. Because heatsinks are designed to to make contact with components, normally the most critical will get the paste (which is a better thermal conductor than pads). Because of tolerances, chips sitting on balls/solder and component height variability, thermal pads are used to take of the "slop" (as mentioned). Because of the viscosity of the thermal grease, it's not made to cover large gaps. I see most of the pads used are ~40 mil, this is way too much gap for the grease to work effectively. It would be like cooling the component by convection and not conduction. -vincinator44