Next you need to prepare the heat sink anew: Remove all of the old thermal compound (silver-gray gunk) by wiping the heat sink with 99 per cent isopropyl alcohol and a lint-free rag. If you bought a used CPU, it may be covered with this goop, too, so clean it off as well. When it's dry, reapply a paper-thin layer of thermal paste to the top of the CPU, spreading it evenly with a business card or an old credit card. Clean up any excess paste and replace the heat sink. Reassemble the laptop and boot it up. Jump into the machine's BIOS setup to make sure the laptop is seeing the CPU properly. Finally, launch Windows and enjoy the performance boost!