Some thermal pastes can contain heavy metals. Some heavy metals are carcinogenic and can cause metal poisoning. Do not handle thermal paste with bare hands and make sure to read the warning labels on your thermal paste before handling.

Once you have cleaned off your old thermal paste, take your thermal paste and apply a small amount between the size of a rice grain and a pea in the plastic window on the CPU chip. Spread the paste evenly with a blunt tool.

After applying your paste, reapply your heatsink.

Make sure the square indent on your heatsink lines up with the CPU chip you added paste to as well as lines up with the screw holes in the motherboard.