Cleaning dust is important! I personally use a small soft paint brush to scrub the surfaces as dust tends to stick to the surface. Then using a can of can’ed air to blow it away with short blasts. Compressed air also works. I don’t find hair driers or vacuums very effective and vacuums tend to damage things do to the static build up they can create in the hose (ESD damage). The fans and the heat transfer fins often need more work.
There are about a dozen companies that sell thermal paste products. Each formulation of paste has different characteristics, Some of conductive, some corrosive, some are thick and some are watery.
The thermal effectiveness of most are within a degree or two. In most systems this is so little a difference it really doesn’t matter that much.
I personally use ArcticSilver and have for years. It offers good effectiveness and is not conductive or corrosive which can damage your system if the material gets onto the wrong areas.
One last note: Thermal paste is intended to fill the pores of the metal and the microscopic gap of the intersection of the chip and the heatsink to improve the transfer of heat. It doesn’t take that much, the trick is to place a dot in the middle and think how that dot will get squished when you press the heatsink down. If you’ve never done this I recommend starting with a small dot press the heat sink down and put on the mountings as needed, then undo the heat sink so you can see how you did. Did the paste get to the edge with just a little falling off the chip do you need more or less? Did the corners get enough? Repeat until you get it right, cleaning off the paste between tries.
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