It is preferred by most here, for that reason - it works pretty well. The paste cures over time, as you said from the heating up and then cooling down. Give it a week or so and temps should fall another 3-5°. To clean out the heatsink fan use a can of compressed air. Take a pencil ot something wood to put into the fan blades to stop them from spinning and creating back pressure or voltage, then blow it out. That should really help it alot. Do that every 6 mos. and it will stay cool and clean. Do the same for all your case fans and GPU fans. Glad it is working.