Anyone who has ever worked on a computer knows how hot they get. A part known as a heatsink dissipates excess heat to prevent the processor from overheating, while thermal grease is used to transfer heat away from the processor to the heatsink. The paste itself dries up and needs to be replaced periodically, which is a relatively easy task when repairing a computer. First, you need to take precautions so you don't harm yourself or your computer. After that, all that remains is to remove the old paste and apply a new one.
Steps
Part 1 of 3: Protect yourself while you work

Step 1. Power off the computer
If the computer is on, open the main menu on the desktop. Select Shutdown or a similar command to completely shut off the power. Don't assume that just pressing the power button will be enough to turn off the power. Often this will only put the computer into sleep mode.

Step 2. Disconnect all cords and devices
If the computer is currently connected to an electrical outlet, unplug it. If you need to turn off your laptop, disconnect it from the charger. Disconnect any other devices connected to the computer.

Step 3. Remove the battery
If your computer is a laptop, turn it upside down. Find the battery compartment. Slide the latch to remove the cover. Take out the battery and set it aside.

Step 4. Hold down the power button
It should be understood that even after you turn off the computer and remove the battery, some of the charge will still remain in it. Press and hold the power button for at least ten seconds. This will release any residual charge that may still be in the computer.

Step 5. Put on your protective gear
Put on a pair of latex gloves before opening your computer and touching its interior. Sebum can interfere with the proper functioning of the components. Also, wear a pair of anti-static wrist straps to prevent your fingers from discharging static electricity, which can also damage parts.
Anti-static wristbands can be ordered online or purchased from a computer store

Step 6. Work in a clean and dust-free environment
Avoid getting dirt and dust particles on the working parts of the computer. Choose a clean area to work with. If your workspace needs cleaning, wait for airborne dust particles to settle before opening your computer.
Part 2 of 3: Remove the old paste

Step 1. Find tips on accessing working parts of your computer in the instruction manual
The sequence of steps to access the heat sink and / or processor of your computer will depend on the computer itself. Check your Owner's Manual for instructions on how to recognize, access, remove, and reinstall required parts. If you do not have a paper version, find the manual on the manufacturer's website.

Step 2. Wipe dust off the fins of the radiator
After you have safely removed the heatsink, remove any dust from the fins. Use a small brush and / or a can of compressed air. Be sure to do this away from other parts of the computer so that dust does not get where it does not belong.

Step 3. Scrape off the old paste
Find the copper core of the heatsink. Scrape off as much of the old thermal paste as you can with the flat end of the mounting paddle (a small hand tool used to dismantle computer parts). Be extremely careful not to scratch any parts, and if you're nervous about this step, skip to the next one.
If you're worried about scratching parts, use a dry cloth or paper towel to wipe off most of the thermal paste

Step 4. Erase the remnants
Even the spudger is unable to completely remove the old paste. Whether you skipped the previous step or not, grab some coffee filters, a lint-free cloth, or cotton swabs. Dampen them with rubbing alcohol or a special cleaner to remove thermal paste. Then moisten with a damp end, loosen and rub off the old paste. If necessary, take new filters, a rag or cotton swabs and repeat the entire process again.
- When you have removed all traces of the old thermal paste, repeat this step one more time to prepare the surface for applying the new thermal paste.
- Cleaners designed for this specific purpose are commonly referred to as TIM (Thermal Interface) cleaners.

Step 5. Do the same with the processor
Examine it for thermal paste where it touched the heatsink. If you find something, follow the same steps to clean the surface. But if you've scooped up the old paste with a scraper, be sure to use a plastic one to reduce the chances of scratches or other damage. If you don't have a plastic spatula, don't try to wipe off the paste.
Pay special attention to where the old paste goes. When you wipe it off, try not to accidentally sweep it onto another part of the processor

Step 6. Repeat for every spot where the thermal grease ends up
If, after the last time, the thermal grease has accidentally spilled onto other parts and dried out, follow the same steps to remove it from them. However, this time, use cotton swabs, paper towels, and other soft materials rather than a spatula, as these parts of the computer may be more fragile. Also, try using a CFC (chlorofluorocarbon) -based spray cleaner for vehicle electrical contacts if the paste has dried out in hard-to-reach areas.
Part 3 of 3: Apply new paste

Step 1. Wait for the heatsink and processor to dry
Please note that after you remove all traces of the old paste, the heatsink and processor must be re-wiped with alcohol or cleaner. Do not apply new paste right away. Wait for them to air dry completely.

Step 2. Squeeze the paste onto the processor core
Apply a small ball of new paste directly to its surface. It is enough to squeeze out a drop the size of a grain of rice. Unless otherwise stated in the instruction manual, squeeze the same amount of paste onto the radiator.
Thermal grease can be found in online stores and computer and other electronics stores

Step 3. Spread the paste over the surface of the kernel
If you've worn latex gloves, bring a clean pair. Otherwise, wrap a piece of plastic wrap around your finger. Spread a ball of paste over the surface of the kernel with your fingertip.
Try not to hit the surrounding green area, but don't worry if this happens. This will not affect the work of the computer. You just have to remove more paste next time

Step 4. Assemble your computer
After you smear the paste over the processor core, your job is complete. Put the computer back together. Look for the building instructions for your computer model in the owner's manual.