PC ComponentsCooling

What Does Thermal Paste Do?

Thermal Paste On Cpu

Thermal paste, sometimes referred to as thermal grease or thermal compound, is a greyish-silver substance. It is a thermally conductive and usually electrically insulating chemical compound. You must apply it to a processor before attaching the cooling solution – whether that be a fan or a liquid cooler.

The thermal paste allows the most efficient transfer of heat possible from the processor to the plate or block of the cooler because it eliminates all space between the processor and the heat sink.

What is Thermal Paste?

Thermal paste is made of a polymerizable liquid matrix. This means it is made out of many different polymers, consisting of many large molecules. The specific thermal paste matrix is typically made out of acrylates, epoxies, silicones, and urethanes.

Some pastes will have silver or other metals in them. The most effective ones are made out of an alloy called Galinstan, but they cannot be used with aluminum heat sinks as they will rust eventually.

How Does Thermal Paste Work?

While the processor and the heat sink may look smooth and like they can fit together with a tight seal, they will naturally have microscopic imperfections, leading to poor heat transfer because air gets in. The air is useless for getting the heat away from the processor. If your processor gets too hot, you’ll start experiencing computer problems like throttling and other worse things.

Putting thermal paste on the processor fills the gaps and prevents air from getting in between the processor and the heat sink of the cooling solution, making the heat transfer as efficient as possible.

Thermal paste is designed to conduct heat away from the processor and creates an airtight seal. This increases how fast the heat can be moved from the processor to the heat sink and dissipated elsewhere.

Long Term Effects

While your computer will boot without having thermal paste, to begin with, you will start regretting not putting any on later. The longer your processor spends overheating, the more likely you will experience stuttering, throttling, blue screens, and seemingly random shutdowns from the computer simply getting too hot to function.

Using thermal paste means your PC will stay cooler for longer. Most thermal pastes are rated for about three to five years, after which it is recommended that you reapply to continue keeping your computer cool. Some pastes are rated to work for seven years, but to be safe, replacing every two to three years is best.

Considerations with Thermal Paste

There are a few things you’ll want to keep in mind when choosing and applying a thermal paste.

Replacing Factory Thermal Paste

When buying computer components, manufacturers may include a tube of thermal paste along with the cooler or heat sink. While a nice gesture, unless the tube of thermal paste says exactly what the polymer composition is, you may not want to use it because it may be cheap ingredients and ultimately fail you before a few years are up.

How to Choose Thermal Paste

When purchasing thermal paste off the shelf, it is reasonable to assume that more expensive pastes mean better quality. However, some of the most costly pastes contain metals that might not work with the components you’ve already purchased, so be sure to check that. Sometimes, the moderately expensive pastes are actually the best for general use.

How to Apply Thermal Paste

Some thermal paste tubes come with a shovel-like instrument called a spreader. Do not use the spreader. If you are not careful, you may damage one of your computer components – i.e., the processor.

Plus, manually spreading around the paste can lead to an uneven distribution making for an uneven heat transfer later. This is because spreading the paste creates air bubbles, and the whole point of using the thermal paste is to avoid the air bubbles already in between the processor and the heat sink.

When applying thermal paste, be careful about how much you put on. Too little paste means air still gets in between the processor and the heat sink. Too much paste lessens the heat transfer effectiveness because the processor and the heat sink are too far away from each other. The excess paste may spill out onto your motherboard and cause further issues.

While there is plenty of controversy on the internet on how to apply thermal paste best, the best rule of thumb is to place a pea-sized drop of thermal paste onto the center of your processor and then allow the base plate of the heat sink to distribute the thermal paste through pressure.

Storing Thermal Paste

While thermal paste may seem expensive, and you might want to keep it to use it the next time you need to apply it, be sure to get the cap screwed on properly and store it in a cool location. For best results, seal it in an airtight bag after that. Also, please do not pull the plunger back out because this will cause it to dry out regardless.

Even with all of these steps, the paste may only last a couple of years. Some avid builders tell you to expect to buy new paste every time. It may seem like a waste, but the costs of using ineffective paste are higher than buying a new tube.

Reapplying Thermal Paste

When it comes time to reapply the thermal paste, remove all of the old paste first. This ensures that you do not have any air pockets or old paste ruining the new paste’s effectiveness. Additionally, if you have to take your computer apart and remove the heatsink from the chip, you will need to reapply thermal paste in the same manner.

Remove the old paste with isopropyl alcohol and wait for the components to dry before applying the new paste.


In short, thermal paste is a necessary part of building your computer. Do not try to skimp out on this important aspect.

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