What Is Thermal Paste and How Does it Keep Your Processor Cool?

When you’re building a PC, you’re more excited about the new processor, graphics card, and RAM instead of the tube of thermal paste you bought. However, thermal paste is vital for your computer’s health; without it, your PC won’t stay on for very long!

Let’s explore what thermal paste is and how it works.

What Is Thermal Paste?

Thermal paste (also known as thermal grease or thermal compound) is a substance applied between the processor and the heat sink. You can buy small tubes of thermal paste at electronics stores, sometimes accompanied by a small shovel-like tool called an applicator.

When you’re building a PC, you’ll need a tube of thermal paste for your PC to run smoothly. Some CPU heat sinks come with thermal paste pre-applied to it so you can install it and go. Some hardware enthusiasts, however, will swear by and manually apply their favorite brand of thermal paste.

The role of thermal paste is to help transfer heat away from the CPU and into the heat sink. The heat sink then expels the heat away from the hardware. This keeps the CPU cool, especially when it’s hard at work processing tasks.

You may also find the term “stock thermal paste.” This kind is thermal paste applied by the manufacturer, such as on a pre-built machine. However, some manufacturers skimp out on the thermal paste and use a compound that’s not very effective at conducting heat.

As such, enthusiasts will often replace this stock thermal paste with their preferred brand of “aftermarket” paste—the stuff you buy off the shelves.

How Does Thermal Paste Work?

CPUs can get very hot, so it’s essential to draw heat from it as quickly as possible. Unfortunately, air is a terrible conductor of heat, so there needs to be as little air as possible between the CPU and the heat sink for optimum transfer.

If you’ve prodded around inside a computer, you’ll know that the heat sink presses tightly against the CPU. This seal may seem good enough to stop air from getting in; unfortunately, even a tight squeeze isn’t enough to keep air out.

The surface of the CPU and the heat sink’s contact plate is covered in tiny grooves and gaps. If not properly sealed up, these gaps allow air between the processor and the heat sink, reducing the heat transfer efficiency between the two.

This is where thermal paste comes in. Not only is thermal paste a good conductor of heat, but it can get into those small gaps and grooves on the surfaces of the hardware. This creates an air-tight seal and increases the rate of heat transfer.

Over time, the thermal paste will get old and dry. The dryness reduces its effectiveness and causes the CPU to get toasty. This occurrence is why people suggest re-applying the thermal paste to prevent a computer from overheating.

Do You Need Thermal Paste?

You may think that thermal paste isn’t as essential in a PC build than the processor or power supply. While a computer will boot without thermal paste, the problem will be keeping it alive while you use it!

Without thermal paste, there isn’t optimal heat transfer between the CPU and the heat sink. As such, the CPU gets a lot hotter than it would be if you had used paste. If the CPU gets too hot, it will overheat; this results in stuttering from throttling, blue screens, and random shutdowns.

While buying thermal paste is the least exciting part of a computer build, it’s a must-have. It allows the heat sink to do its job better and protects your computer from burning out and shutting down.

If you’re wondering if you need thermal paste because you’re worried about messing up your brand new expensive processor with gray goop, try getting a heat sink with paste pre-applied. The paste may not be the best kind on the market, but it does make installation easier.

How Do You Apply Thermal Paste?

Given the importance of thermal paste, there’s a disturbingly volatile debate on the best way to apply it. If you scour the internet, you’ll find theorems, strategies, and passed-down advice for application. The above video shows how varied these paste application patterns can get.

The simplest method of application is to place a pea-sized drop on the middle of the processor. Then, attach the heat sink to the processor, applying pressure on the four corners equally. This ensures the thermal paste is squashed and distributed evenly along the surface.

If your thermal paste comes with an applicator, you can use it to get an even spread of paste. Some people like this method to ensure the spread is perfect before they clamp the heat sink down on the processor.

Some methods talk about a line-based application that spans across the cores of the processor. Of course, you’ll need to know where the cores are on the processor, so it’s not for everyone.

In our guide on how to choose and mount a CPU fan, we link to an Artic Silver application website that tells you the ideal paste application method depending on the CPU model. This is great for studying different ways and choosing the method that suits your hardware best.

Regardless of what method you pick, it’s important to ensure no bubbles or gaps occur in the paste. These allow pesky air to get in and hinder heat distribution.

What’s the Best Thermal Paste Brand?

Selecting the best thermal paste is pretty tricky, as everyone has different opinions on which one works best for them. However, you can choose the best brands by looking at test results and basing your decision off of raw data.

To examine thermal paste efficiency, a tester first measures a computer’s idle temperature. Then, they apply a brand of thermal paste to the processor. The computer is then put through a stress test.

The tester checks the max temperature the processor hits during the stress test. They then compare the stress test temperature to the idle temperature from before. The smaller the difference between the idle temperature and the stress test temperature, the better the thermal paste is at removing heat.

To see the best thermal paste brands, try this benchmark spreadsheet and look for the compound with the lowest change in temperature. The spreadsheet will also note if a brand of paste is hard to apply, so be sure to note that if you’ve never used thermal paste before.

Keeping Your PC Cool

While thermal paste isn’t required to boot up a computer, it’s very useful for keeping temperatures down. As such, you should always apply thermal paste when building a computer, even if the internet can’t agree on the best way to distribute it!

If you want to keep your processor chilly, why not check out the best cooling systems for your PC?

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