Why Does CPU Need Thermal Paste?

Why Does CPU Need Thermal Paste

Thermal paste, also referred to as thermal grease or thermal compound, is a substance used in between your processor and heat sink. In electronics stores, you can purchase tiny tubes of thermal paste, sometimes with an applicator, a tiny shovel-like tool.

In order to move heat from your CPU (Central Processing Unit) and into heat sink, thermal paste is used. This heat is then dissipated by heat sink away from your hardware.

This keeps your CPU from overheating, particularly when it is busily processing tasks. If you are wondering why does CPU need thermal paste, read on to know more.


  • Thermal pastes are a necessary component required for heat removal from your computer.
  • How long thermal paste lasts and how effective it is in reducing heat depends on several factors including its composition, computer usage and external environmental conditions.
  • CPUs cannot be used without thermal paste, so it is necessary to keep a spare tube of this compound handy or you can try a homemade mixture.

Reason Why CPU Need Thermal Paste

Why Does CPU Need Thermal Paste

Your CPU is built from a core of millions of tiny electronic switches. A little heat is produced each time a switch is used.

Heat builds up quickly when millions of these switches are activated thousands of times per second.

Your CPU works very hard and may become very hot when running demanding programs, such as computer games.

Thermal production is also increased by overclocking. In order to protect this chip from heat damage, a heat sink is attached to your CPU.

In order to maximize surface-to-surface contact with your CPU, bottom surface of a heat sink is made to be incredibly smooth.

On the other hand, flaws and pits in your CPU’s wafer structure permit tiny gaps that lower heat sink’s efficiency.

Thermal paste comes into play in this situation. It is a thin layer made up of a number of different substances that thermally connects your CPU and heat sink.

Any crannies, openings, or flaws that might permit air pockets between this chip and heat sink are filled.

Thermal paste is created from specific materials that achieve this purpose rather well because in order to be effective, thermal grease must conduct heat. Some varieties perform better than others at transferring or conducting heat.

While less expensive compounds are silicon-based, more expensive thermal grease contains silver particles for maximum effectiveness.

Ceramic grease is a mid-grade substance that, in numerous independent tests, outperforms silver-based substances.

Heat is removed from your processor and drawn upward into fins of a heat sink. A properly installed heat sink uses this material to maximize contact, so that heat is then dissipated by a fan.

Without thermal paste and a heat sink, your CPU should never be used. Heat can quickly build up to the point where its core melts, rendering your device useless.

What is Thermal Paste Made of?

The two main components of thermal paste are a polymer base and a thermally conductive filler. It is also known as thermal interface material (TIM), thermal compound, heat sink compound, and heat paste.

Typically, a high-performing thermosetting epoxy resin with strong mechanical and adhesion properties as well as thermal stability serves as a polymer base.

Conversely epoxy resins have a very low thermal conductivity, so its filler, which can make up as much as 80% of weight in some pastes, is what gives thermal paste its thermal conductivity.

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The most popular types of thermally conductive filler are boron nitride, aluminum nitride, alumina, zinc oxide, ceramic, copper, and silver.

Silicon Based Thermal Paste

Since silicone-based thermal pastes are inexpensive and simple to use, they have become very common.

In contrast to other varieties of thermal paste, their thermal conductivity is lower. They are made up of a silicone oil base and a powdered metal oxide that acts as a thermo-conductive material.

One disadvantage is that silicone oil may separate and ooze from this thermal paste, resulting in problems with solderability and dewetting which is inability of a conformal coating to cover a surface evenly due to improper material mixing.

Some manufacturers advise rotating its tube every few months to prevent dewetting, which can also happen while thermal paste is in its tube.

They are typically light gray in color, and are non-curing and have an operating temperature range of -58°F to 400°F.

Metal Oxide Thermal Paste

Even though some thermal pastes are named metal oxide, they are still primarily silicone-based, even though their silicon content may be much lower than in typical silicon-based thermal pastes.

A metal with a very high conductivity, like silver, is typically its main component, though other metal oxide compounds and carbon may also be present.

While having minimal electrical conductivity, metal oxide thermal pastes outperform conventional silicon-based compounds in terms of thermal conductivity. They are simple to use and ideal for high-performance applications.

Liquid Metal Thermal Paste

They are the most efficient because this compound is almost entirely made of metal, typically gallium, are among the most well-liked among overclockers.

A soft metal with a low melting point and extremely high boiling point is gallium.

When combined with indium, another soft metals, their melting point decreases from 30°F to -2°F, keeping this thermal compound as a liquid at room temperature, while maintaining a high boiling point of 2370°F.

Little to no evaporation occurs as a result of this high boiling point. In addition, liquid metal thermal pastes have highest thermal conductivity of any thermal paste.

Liquid metal thermal pastes do, however, have some limitations.

Since they are made entirely of metal and are electrically conductive, care must be taken when applying this paste to prevent it from spilling onto pins of components or tracks and causing short circuits.

Therefore, applying liquid metal thermal pastes is more challenging, and manufacturers frequently provide special instructions.

Another disadvantage is that its main component, gallium, reacts with aluminum to form an aluminum alloy that is touch-fragile.

As a result, aluminum heatsinks cannot use liquid metal thermal pastes.

Ceramic Based Thermal Paste

Silicone-based thermal pastes tend to dry out, and they frequently have a higher silicone to filler ratio than other varieties of thermal paste, which results in an average reduction in thermal conductivity.

Ceramics, like boron nitride, have gained popularity in production of thermal pastes because they offer high thermal conductivity, a low coefficient of thermal expansion, are resistant to corrosion and erosion, and provide electrical insulation.

Ceramics are regarded as a superior filler when compared to other fillers’ production costs.

A cutting-edge synthetic ceramic material called boron nitride can be obtained as a solid and a powder. It belongs to a group of ceramic fillers and provides superior electrical and thermal insulation.

Other fillers in thermal pastes include aluminum oxide, aluminum nitride, beryllium oxide, and zinc oxide, though it is the most frequently used ceramic filler overall.

Thermal pastes made of ceramic typically provide long-term stability over a temperature range of 5°F to 400°F. Occasionally, silicone-free thermal paste is also used to refer to ceramic-based thermal pastes.

Carbon Based Thermal Paste

Carbon fillers, which offer high thermal conductivity, mechanical strength and stability, and durability, are another type of thermal pastes.

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Graphene, graphite, carbon nanotubes, and carbon nanofiber are examples of common carbon fillers.

Since, carbon-based thermal pastes lack metals, they are not electrically conductive. They have an eight-year lifespan and are simple to apply.

Carbon fillers are a great thermal paste because of their high thermal conductivity and wide operating temperature range.

Thermal Paste Alternatives

One of the most important parts of PC assembly is thermal transfer compound, also known as thermal paste.

After investing hundreds of dollars or euros in every other component needed for its build, it is not unusual to forget to buy a tube of cheap compound.

There are commonplace substitutes for thermal paste that can temporarily replace commercial-grade thermal pastes if you’re in a desperate enough situation.

Cocoa and Hazelnut Cream

Due to their soft consistency, cocoa and hazelnut spreads are perfect for creating a reliable thermal paste.

Keep in mind that they should only be used for a couple of days at most.

A few load tests lasting around 15 minutes can demonstrate effectiveness of these pastes.

Your processor’s temperature will remain low throughout operation.

Toothpaste Mixture

Thermal paste can also be successfully replaced by toothpaste. After a few days, especially if operating temperatures are high, its structural integrity degrades.

Additionally, a small amount of Vaseline may be added, in the following ratio: 80 percent toothpaste and 20 percent Vaseline.

To keep toothpaste from drying out, apply Vaseline Grease. Apply a thin layer evenly to your CPU using a syringe filled with this prepared mixture.

Although in theory it should last for three to four months, it is preferable to maintain control of this situation by replacing it every 15 to 30 days.

Small spots might appear on this metal when it is being removed. However, these stains can be removed using a little cotton wool and 90 percent alcohol.

This paste can then be used once more. Some toothpaste varieties are not appropriate for this job. Thermal conductivity of different toothpaste varieties varies.

To generalize about this product category would be impossible. As a result, it should only be used in specific circumstances.

Since toothpaste leaves micro holes full of air, it is not a suitable replacement and should not be used.

The following could be primary qualities to look for in your toothpaste:

  • Strength of adhesion to metal surfaces
  • Continuity at a range of temperatures
  • Remaining operational time before it expires.
  • Ability to repair minor surface flaws.
  • Electrical insulation.

An old credit card can be used as a brush to evenly spread this new paste.

Aluminum Powder

Mixing Vaseline oil and very fine, smooth aluminum powder is another option for thermal paste.

To prevent presence of tiny air bubbles, this mixture must be blended for at least 10 minutes.

A piece of aluminum can be abrasively ground into powder at home or purchased in specialty shops.

Vaseline oil is a stable substance with a high boiling point and when aluminum is submerged in this oil, it does not oxidize.

Diaper Rash Cream

Zinc oxide, the primary ingredient in commercial thermal paste, is widely present in this kind of cream.

On heat sink, you can apply a thin layer, and it will function flawlessly for 5–6 months. Clean your CPU surface with alcohol before spreading this new mixture.

Other Options

A chemistry enthusiast might discover a method to create an emergency thermal paste from one of these countless trial solutions.

Here are some additional concepts that might work, perhaps on a dated CPU.

Despite being thermally and electronically stable, some materials can only withstand high temperatures for a short period of time before degrading gradually.

You can access following products either separately or in combination:

  • Yellow cheese
  • Hair wax
  • Moisturizer cream
  • Butter
  • Banana
  • Card
  • Adhesive for dental implants
  • Spread of cheese
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Additionally interesting thermal coefficients are those of ketchup and mustard. Unfortunately, both products lose their potency in 24 to 48 hours.

Although they melt after a short while, butter and moisturizer are also fantastic short-term fixes.

Your motherboard and any nearby electronic circuits could also be at risk from oil that might accidentally drip onto these circuits.

How Long Does Thermal Paste Last?

Thermal paste typically has a lifespan of up to five years, if not longer. However, it should be replaced every two to three years.

Quality and effectiveness of thermal compound may deteriorate over time, even if it is not used, so it is advised to not store it for longer than three years.

Duration of various thermal compounds’ effects on a device depends on a few different factors. The following are typical variables that affect how long a device’s thermal compound will last.

Heavy use

It is advised to replace thermal paste more frequently for computers that are used frequently than for heavy users.

Extreme computer use also increases the likelihood that it will overheat, which could reduce thermal paste’s shelf life and cause overheating.

Thermal paste quality

Obviously, high-quality items will last longer. This also holds true for thermal paste that is being used in your computer.

Type of thermal compound is another consideration; if it has not dried out yet, you can still use some pastes when separating cooler from your system’s motherboard.

Environmental factors

When it comes to lifespan of thermal paste, the environment also has a significant impact. Storage is best done at room temperature.

Quality and shelf life of thermal paste may be impacted by storing it near a heat source or in a cold environment.

Attics and windows that receive direct sunlight are just two examples of storage locations to stay away from.

Excessive paste

It is wrong for people to believe that overcooling their CPU or GPU by applying excessive amounts of paste will be effective and quick. Additionally, if your piece has too much paste, it could leak and cause damage.

Removing coolers

Naturally, you would need to reapply thermal paste if you removed your coolers from your CPU or GPU.

Even among seasoned computer builders, this is standard practice. However, some high-end thermal pastes allow for reuse if they haven’t dried out.

Do CPUs Come with Thermal Paste?

No CPU comes with thermal paste applied to it, but stock cooler that is included with your CPU might; therefore, if your CPU is included with a stock cooler, you should not need to use additional thermal paste.

Pre-applied layer of thermal paste that most stock coolers have on their baseplates usually provides adequate heat conductivity between your CPU and cooler.

Thermal grease, frequently in the form of a thin thermal pad, is included with CPUs that are sold with a heat sink and fan in a retail box.

In most cases, using this included thermal pad, heat sink, and fan voids your CPU’s warranty.

So, do not forget to buy thermal grease and use it carefully in accordance with accompanying instructions if you’re purchasing an original equipment manufacturer (OEM) CPU and providing your own heat sink and fan.


Now you know why does CPU need thermal paste, you can easily make a well-informed decision about which thermal paste you should purchase and use based on all the detailed information mentioned above.

Purchase wisely and apply carefully to protect your computer from getting damaged due to regular usage.

About Taylor

AvatarTaylor S. Irwin is a freelance technology writer with in-depth knowledge about computers. She has an understanding of hardware and technology gained through over 10 years of experience.

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