Everybody focusing on the Thermal Paste.
For safe application, switch off laptop, remove battery and AC power connections. Let the laptop cool down.
Thereafter, optionally, remove battery connections to the motherboard.
Take multiple images to have proper reference. Thereafter locate screws holding the heatsink. There will be MANY screws, some of which may also vary in size. Remove them slowly.
Check the underside of the heatsink to see WHERE it makes contact. It could be absorbing heat from multiple components. Ensure you apply thermal paste to these areas.
Clean the heatsink and the CPU with proper cleaner (Isopropyl Alcohol). Wait for it to dry off completely.
Always use little, (pea size) amount of thermal paste. Honestly, more than the thermal paste, its proper application is critical to ensure proper contact between the CPU and the Heatsink.
Remember, the intention of thermal paste is to minimize grooves, empty pockets, and smooth out the undulations to improve heat transfer while minimizing hotspots.
Do not let the thermal paste sit for long. Quickly reapply the heatsink and then very carefully tighten the screws. NEVER overtighten.
