Before installing a new heat sink, you must remove all the old thermal paste from the CPU surface.

Use the flat end of a spudger to scrape up the old thermal paste from the CPU.

Use high concentration (more than 90%) isopropyl alcohol and a microfiber cleaning cloth to remove all the thermal paste residue from the CPU.

Don't touch the CPU or let any dust or debris settle on it—even a fingerprint can interfere with heat dissipation.

Wait for the isopropyl alcohol to dry completely before applying any thermal paste.