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How to Apply Thermal Paste?

Thermal Paste can keep your CPU cool and efficient by properly transmitting the heat from it to the heatsink. It can work without any issues for a few years. But if you bought a new CPU or trying to upgrade the CPU Cooler, then you want to replace the old thermal paste with the new one. This might seem like a daunting task (especially for novices) but with proper tools and preparation, anyone can do this job in a short time. If you are wondering how to apply thermal paste on a CPU, then this guide is just for you.

Here, we would like to take you through a step-by-step guide on how to clean the existing thermal paste, choose the right thermal paste, and finally how to properly apply fresh thermal paste. So, let’s get started.

A Brief Note on Thermal Paste

The CPU (the processor) in a computer generates a lot of heat during operation. A heat sink is a metal block with a lot of fins that sits on top of the CPU and directs the heat away from the CPU using thermal conduction. Thermal paste, also known as thermal compound or thermal grease, acts like a bridge between the CPU and the heat sink.

It is a thick, paste-like substance with a crucial property: high thermal conductivity. This means it efficiently conducts heat away from its source (CPU in this case).

How Thermal Paste Works?

The surfaces of the CPU and the heat sink, although appearing smooth, have microscopic imperfections. These imperfections create tiny air gaps that trap heat.

Thermal paste steps in to fill these air gaps. When applied correctly, a thin and even layer of thermal paste creates a complete connection between the CPU and the heat sink. This eliminates the insulating air pockets and allows heat to flow smoothly from the CPU to the heat sink. The heat sink then transfers the heat away from the CPU, keeping it cool and functioning optimally.

Without thermal paste, the air gaps between the CPU and the heat sink would act like tiny roadblocks for heat. The CPU’s heat would struggle to reach the heat sink, causing the CPU temperature to rise. A hot CPU can lead to throttling, a self-preservation mechanism that forces the CPU to slow down to avoid damage. This translates to sluggish computer performance and potential crashes.

Why Do You Need to Apply Thermal Paste?

You might have to apply thermal paste when you are first installing a CPU. Some new coolers come with pre-applied thermal paste. In this case, you can directly install the CPU and the cooler without applying any thermal paste.

If the new cooler doesn’t have a pre-applied thermal paste or if you are reusing an old CPU Cooler, then you have to apply a fresh stock of thermal paste. The same applies even if you are changing your CPU cooler (upgrading to a new cooler or a water-cooling solution). In either case, there will be an additional step of cleaning the old thermal paste first.

Over time, thermal paste can dry out or lose its effectiveness, leading to increased CPU temperatures. Experts recommend checking and potentially reapplying thermal paste every two to three years. This way, there will be an efficient heat transfer and we can prevent thermal throttling, where the CPU slows down to avoid overheating.

How to Apply Thermal Paste?

Let us now see how to apply thermal paste on a CPU. Before proceeding, we would like to bring up that the steps might vary slightly if you are building a new PC and freshly installing the CPU and cooler when compared to applying (or rather re-applying) thermal paste on an old (working) PC.

1. Choose a Thermal Paste

There are several popular brands of thermal paste such as Arctic, Corsair, Thermal Grizzly, Noctua, Cooler Master, and Thermal Take. Browse for a thermal paste and choose one that fits your requirements (temperature range, viscosity, density, volume resistivity, etc.).

2. New PC? Install the CPU

If you are building a new PC, then the first job is to install the CPU. Both Intel and AMD nowadays have CPUs with LGA socket (pins on the socket and pads on the CPU). All you have to do is drop the CPU in the socket and lock it (this is not a detailed guide on how to install CPU).

3. Clean the CPU and Heat Sink Surfaces

Already have a working PC? Looking to replace the CPU or Cooler? Then we have to first remove and clean the existing thermal paste from the CPU and heat sink first. We have made a detailed step-by-step guide on how to clean thermal paste off CPU. Here’s a simplified version. Take a lint-free cloth (microfibre cloth) and wet it with isopropyl alcohol (90% or more).

Thermal Paste Renewal

Gently clean the surfaces of the CPU until you remove all the thermal paste off them. You can use kitchen towels, cotton swabs, or coffee filter if microfibre cloth isn’t available. Repeat the same steps to clean the surface of the CPU cooler (heat sink) as well.

4. Use Sand Paper (Mild Emry Paper) to Clean Surfaces (If Necessary)

Some authors recommend using mild sand paper (Emry paper) to clean any left-over residue. We wouldn’t recommend it though. Use this only of you are unable to clean the surface using the previously mentioned material (microfibre cloth, paper towel, etc.). Instead of sand paper, you could scrape the hard and dry thermal paste with a plastic scooper or spatula first and then try cleaning with microfibre cloth dipped in isopropyl alcohol.

5. Apply Thermal Paste

The next step is to apply the thermal paste. Do we have to apply thermal paste on both the CPU and the Cooler? No. We only have to apply thermal paste on the CPU. When we place the cooler on top of the CPU, the same thermal paste will create the thermal connection.

If you are installing a new CPU Cooler that comes with pre-applied thermal paste, then you don’t have to worry about anything. Simple go ahead with the installation of the cooler. But for all the other cases, continue with the remaining steps.

The new thermal paste usually comes in a syringe so that we can easily squeeze it on the surface. If in case you have a different container, then you have to make use of the plastic spatula that comes with it (if not, you can use an old credit card).

Now comes the important question, how much thermal paste should we apply on the CPU? There is a lot of discussion on the quantity and pattern of the thermal paste that we need to apply. We even made a dedicated guide on the best thermal paste patterns. Check that for an in-detail guide on thermal paste patterns. For the “How to Apply Thermal Paste” guide, let us see some of the basic patterns.

Dot Method

As the name suggests, you need to squeeze out the thermal paste in the form of a dot, usually a pea sized, exactly in the middle of the CPU. When we install the CPU Cooler, it will spread the thermal paste for the entire surface. Make sure that the quantity of the thermal paste is so much that the heat sink will not spread it out of the CPU bounds.

Thermal Paste

Never forget to check the capacitors installed around your CPU. And always use the paste according to that size. The dot method is commonly used and is also safe. It’s highly unlikely that you’ll cause any spillage.

Cross Method

Like the dot method, the cross method is another effective way of applying the thermal paste. You need to form a cross with the thermal paste starting from one corner and ending on the other (not the edges). You should do it in a way so that you see an ‘X’ or cross on the CPU.

Always stay away from the edges. While drawing the crosses, make sure that you’re well within the boundary of the CPU. There are several other methods where you can draw different shapes like the ‘line’ and ‘spiral’ methods. However, the results they yield are almost the same.

6. Install the CPU Cooler

Now, you need to lower the heatsink using a gentle but equivalent force on all sides. Make sure not to slam it. You should apply light force for placing the water block or the base plate of the cooler on your CPU. Hold it that way until you attach the cooler with the mounting mechanism.

Make sure to apply the force in a way that does not let the cooler slide. Also, you need to ensure that the pressure evenly distributes the thermal paste that you have applied. Light pressure is always the key, as if you increase the pressure, it can damage the CPU or the motherboard.

It is important that you tighten the screws of the cooler in a diagonal pattern over the motherboard. It should ideally form an “X.” This is done to make sure that even pressure is being applied on all sides.

7. Connect CPU Fan(s) to Motherboard

After installing the heat sink, you can plug the CPU fan into the CPU_FAN slot on the motherboard. In case you have multiple fans, then plug all those fans into the respective slots (CPU_OPT, or a central controller hub).

8. Double-check Your Work

Now that you’re done installing the CPU Cooler (either regular air cooler or a water cooler), you need to check whether everything works fine or not. Make sure that there’s no thermal paste spilling on the edges of your CPU. In case there’s some paste spilled on the edges; you need to clean using isopropyl alcohol. And if there isn’t any spillage, then congratulations, you did it right.

Things to Consider While Applying Thermal Paste

You can always apply the thermal paste using any of the methods that we mentioned in the pattern guide. However, you need to ensure that the amount of paste used is adequate. If you use less than the required amount of paste, the heat conduction will be poor, and you’ll face overheating problems with your CPU.

And if you apply more than the required thermal paste, there can be a different issue. Although it’ll conduct the heat properly, there are chances that it will spill on the edges. It may not look like a big problem but cleaning it off using alcohol and starting the process again is quite an issue.

If you go with the spreading the thermal paste before installing the CPU Cooler, then make sure that there are no air bubbles while flattening the paste.

Frequently Asked Questions

Is there a difference between thermal pastes?

Answer: Thermal Pastes from reputable brands are almost identical. There might be a difference of 1°C in the temperature performance between thermal pastes from two brands. But apart from that, almost all thermal pastes are identical.

Can I use thermal paste on other components?

Answer: You can use thermal paste on all power electronic devices that utilize a heat sink to transfer heat away. These usually include transistors and diodes.

Can thermal paste cause short circuits?

Answer: Almost all thermal pastes (at least the ones that are designed for use with computer components such as CPU and GPU) are thermally conductive but electrically non-conductive. So, the chance of causing a short circuit due to thermal paste is none. If the thermal paste is electrically conductive, then the manufacturer will mention or highlight it in the specifications. We should be very careful when using such products or shouldn’t use them at all.

Do I need to reapply thermal paste if I upgrade my heatsink?

Answer: Yes. When you are upgrading the heat sink (CPU Cooler) of your CPU, then you need to reapply thermal paste. If the new heat sink comes with pre-applied thermal paste (some models do come with this), then you don’t need to apply a fresh stock of thermal paste but only clean the old thermal paste off the CPU.

What is the thermal conductivity rating of thermal paste?

Answer: The thermal conductivity of thermal paste indicates how effective the thermal paste is in conducting heat away from the CPU or GPU to the heatsink. It is usually in the range of 3 to 12 W/mK (Watts per meter-Kelvin). Higher thermal conductivity values mean the paste can transfer heat more efficiently.


The thermal paste may not be a topic of concern for most users out there. However, for professional gamers, or PC builders, it can prove to be really effective. With the correct application and regular reapplication, the thermal paste can maintain an optimum temperature for your CPU and GPU. We hope that this guide on how to apply thermal paste could help you understand the basics of thermal paste and its application procedure. If you have any comments, queries, or question, do express them using the comments section.

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