How to Apply Thermal Paste {Step-by-Step Guide}

Thermal paste is used as a heat transferring agent that you can fill in the microscopic gaps that are present between two flat metal surfaces.

When you’re assembling your computer, you would have noticed that the CPU and the Cooler are against one another, this means that two flat metal surfaces are naturally against each other.

Due to which, air-filled gaps affect the rate at which the coolant absorbs heat from the CPU.

Thermal paste comes in different material, like ceramic and metal-based pastes and solid and even waxy thermal pads.

Sometimes coolers come with pre-applied pads, but they usually don’t. We recommend using a paste in these situations, Arctic Silver 5 and Arctic Silver Ceramique are the two top best thermal pastes out in the market.

A lot of people who assemble PC’s find this part the most complicated when compared to any other assembly part.

This is mainly because the CPU chip is relatively tiny, delicate and also expensive. The chip of the CPU might be the most expensive part of the entire system.

If you mount the cooler wrong or apply the thermal paste in the wrong way, it could affect the performance of the system and will increase the number of times your system crashes.

There are two types of thermal paste or grease, and the first one is the non-conductive and the second one is conductive.

The non-conductive thermal paste composition usually consists of silicone and zinc thermal greases. The conductive thermal’s composition includes silver, copper and aluminum-based paste.

The conductive thermal grease is stronger and must be used very carefully, or they can cause electrical shorts.

Especially if its applied to the microprocessor’s pins or on the electrical pathways of the circuit board.

Steps For Applying Thermal Paste

Choosing a Good Paste

As mentioned above, almost all the thermal pastes contain silicone and zinc oxide in them, and some of the expensive ones contain heat conductors like silver or ceramic.

The ones that contain silver and ceramic are more effective at heat transmission but, the basic thermal paste will fulfill the needs of almost all the applications.

If you have plans for overclocking your computer, we recommend you buy the expensive thermal pastes that mainly contain silver, gold or even copper.

These are the most conductive metals and will increase efficiency.

Cleaning the CPU Chip and the Heat Sink Surface

The first and most important step is to clean the surface with a cotton ball or a cotton swab, it should be dampened with isopropyl alcohol.

70% of alcohol content is a good amount, but 90% percent of alcohol content is even better. Higher the alcohol percentage the better.

Sanding the Surface If Necessary

The two surfaces that are the CPU and the Cooler will be flat, and this would eliminate the need for thermal paste.

But if your heat sink fancy term for cooler! base is rough, you can wet-sand it using a fine grit paper, or you could even use an emery cloth to make it smooth.

This step is required only and only if you’re looking for ultimate results in the cooling performance.

Thermal paste was originally designed to fill the gaps that are present between two flat surfaces when you join them.

And since it is always not possible to make a surface without any imperfections, thermal paste will always be necessary. Good news for the companies that produce them!

Applying Heat Sink to Circular Based Coolers

Take a tiny drop of thermal paste and place in on the center of the cooler base.

This drop should be extremely tiny, and it should be smaller than a grain of rice or a BB. If anyone has told you to use a pea-sized drop please do not listen to them!

It was way too much paste and can easily end up on the motherboard, which you definitely don’t want.

There is nothing else you have to do here, remember that you don’t have to spread the paste for circular coolers, as the pressure of being applied will spread it evenly throughout the surface.

Attach the Heat Sink to the Processor

Place the heat sink with even pressure from all the sides, and this will spread over the entire surface making a thin and even layer that will fill all the gaps and avoid excess build up.

As and when heat is applied the paste will become thinner and spread towards the edges. And this small amount of paste will go a long way.

Removing the Heatsink after Installing

you want to break the seal that you created while installing your heatsink, it is possible, but if you want to install it again, you’ll have to start the process all over again by cleaning off the old paste and then reapplying it.

Hence, we recommend that you let it be and do not fiddle with it too much and keep checking if your paste has been applied.

Reconnecting the Fan to the Motherboard

The CPU fan wire should be plugged at the CPU fan socket as it mostly uses the PWM function which lets the computer adjust the fan speed without fluctuations in the voltage.

Booting the system

The only thing you have to check is that if the fan is spinning. Press the F1 key or the Del key during post and enter BIOS.

Check the temperature of the CPU, it should be below 40 degrees Celsius when idle, and the same thing can be applied for GPU.

This is one of the simplest ways on how to apply thermal paste.

Applying Heatsink to Square Based Coolers

Applying thermal paste to a square based cooler is a little more complicated and challenging when compared to the circle based cooler.

This was because you could just simply apply a dot and it would spread evenly with pressure and result in full coverage.

There are a few methods you can use, all of these methods have claimed to be the right and the best way.

So let’s go through all the popular methods on how to apply thermal paste:

  1. The line method: in this method, you draw two lines of the thermal paste on the base of the cooler. Make sure the lines are parallel and spaced well so that they are placed a third of the processor’s width.

  2. The cross method: as the name suggests, you draw an “x” pattern on the cooler and not two parallel lines like the previous method. But the length and thickness of the lines of the “x” can be the same as the previous method.

  3. The spread method: This is the most used method, but this method needs a little more effort. Put a small amount of thermal paste on the base of the cooler. Using a plastic bag or a finger protector, use it and spread the paste across the surface as evenly as possible. Just make sure the entire surface should be in contact with the processor and also make sure that the paste is not applied too thick.

Installing the Heatsink

If you’re using the line method, apply pressure to the heat sink as you install it and make sure it covers the entire surface.

And if you’re using the spread method, you have to install the heating disk at a slight angle to prevent bubbles from forming.

These bubbles usually form due to the thin spread of thermal paste.

Reconnecting the Fan to the Motherboard

The CPU fan wire should be plugged at the CPU fan socket as it mostly uses the PWM function which lets the computer adjust the fan speed without fluctuations in the voltage.

Booting the system

The only thing you have to check is that if the fan is spinning. Press the F1 key or the Del key during post and enter BIOS.

Check the temperature of the CPU, it should be below 40 degrees Celsius when idle, and the same thing can be applied for GPU.

After this, you’re completely done. We don’t recommend you doing this over and over as this could cause a lot of air bubbles.

Storage and Clean Up of Heatsink

The best and the simplest way to keep your thermal compound fresh for future usage, make sure to replace the cap after each use.

If you’re using if from a syringe, remember to store the syringe tip down so that any separation between the particles will end at the back of the syringe.

Storing it in a cool place like a refrigerator will minimize the possibility of separation with time.

But this will not affect the performance of the compound, and it doesn’t matter if it un-separated or remixed compound.


When you check the temperature of the CPU, and if it is not below 40 degrees Celsius, it is a problem that has to be looked into.

You can trace the problem using these 11 things listed below :

  1. It could have been because you cleaned the heat sink with an oil based cleaner filled with microscopic gaps that would have contaminated the interface.

  2. There could have been existing thermal paste or grease material that was not completely or properly removed.

  3. Maybe the heat-sink was installed properly. You could have trouble if the thermal paste were applied too thick.

  4. The measurement would have been taken on the cold side of the core of the thermal compound or the thermal junction where thermal compound from the junction contaminates the probe.

  5. The measurement probe could have been moved around when the chip was removed while cleaning off the previous paste.

  6. You can also face issues if you don’t allow it to go through its break-in period. (This could vary, but the minimum is usually 25 hours.) temperatures will drop eventually.

  7. The heat sink or the cooler could have been contaminated by a fingerprint, a speck of dirt or even an eyelash. It can get contaminated easily, and you must be extremely cautious while going through the process.

  8. If you heatsink fan is not fixed properly and is unbalanced, it could cause excessive vibrations and damage the interface.

  9. Anything that is interfering with making proper contact between the CPU core and the heatsink like a manufacturing defect or a bent shim.

  10. Check if the heatsink was plugged back in after the applying the thermal paste.

  11. Check if the ambient temperature where the computer was located changed over time.

Precautions on How to Apply Thermal Paste 

  • Do not put it in your mouth, do not eat it.

  • Keep away from children, or from any place where the children have access to it.

  • Keep it really far away from your pets and any place they could get it from.

  • Never turn on a computer without attaching the heat sink carefully and properly mounted on the CPU and thermal compound between the CPU core and the heatsink. A high-performance CPU could be permanently damaged in about 10 seconds if it was not properly cooled.

FAQ’s: How to Apply Thermal Paste

1. Is it okay to use a PC cooler without thermal paste?

We would not recommend using a CPU cooler without a layer of thermal paste between the cooler and the CPU.

If you still choose to do so, the heat will not transfer properly from the CPU to the cooler. And this will damage the CPU eventually.

2. Is it necessary to use alcohol or can we use water or anything else?

It doesnot recommended to use water or any form of oils or any other conducting liquid should not be used. Is it okay to use thermal paste that is seven years old?

You can use it as long as it is not solidified. A lot of carbon-based products last for around eight years. You can always check the manufacturing data on the tube.

This brings us to the end of how to apply thermal paste. The method you pick mainly depends on the type of cooler you have. It’s not very difficult so don’t stress on it. And we hope this answered your question “how to apply thermal paste.” Good luck!

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