Power off the computer and unplug it
Remove the CPU cooler
Clean old thermal paste from the CPU and cooler with isopropyl alcohol and a lint-free cloth
Let both surfaces dry completely
Place a small pea-sized dot of thermal paste in the center of the CPU
Do not spread the paste unless the manufacturer specifically recommends it
Reinstall the cooler straight down onto the CPU
Tighten the cooler evenly
Reconnect the cooler fan cable
Power on the computer and check CPU temperatures