Blob of Thermal Paste on CPU

How Often Should You Replace Thermal Paste and How to Do It

If you have any interest at all in how computers work, you will most likely have heard of thermal paste. This substance is known by a number of other names, as well, including Thermal Interface Material (TIM), heat paste, thermal gel, thermal grease, and CPU paste, but it is all essentially the same thing.

If you want to dive into the satisfying task of building or upgrading your own PC, you should definitely have some knowledge about the use of thermal paste and how to apply it. This article will give you some insight into why you should use heat paste, when you should replace it, and how to apply it.

Why Should You Use Thermal Paste?

Thermal Paste in a tube on a white background.

The purpose of thermal paste is to close the microscopic gaps in the metal plates of both the Integrated Heat Spreader (IHS) of a CPU chip and the baseplate or water block of a CPU cooling unit. This is to prevent warm air from being held in these imperfections, where it can cause the CPU to overheat.

These surfaces may appear flat to the naked eye, but they are not, and although your computer will start up without thermal paste, doing so would very soon cause overheating and its resulting issues. Therefore, if you want your computer to run optimally for years to come, you should learn all you can about thermal paste and how to use it.

When Should You Use Thermal Paste

Installing CPU Cooler Fans
Installing CPU Cooler Fans

If you buy a pre-built PC, it will come with thermal paste already applied between the CPU and the cooler, but if you are building your own, you may need to apply it yourself. There are some cooling units that come with thermal paste pre-applied, so be sure to check for this before applying it yourself. Too much thermal paste is just as bad as too little.

Whether you applied the first blob of thermal paste yourself or it was done by someone else, there will come a time when your PC will need its paste reapplied. Most sources agree that thermal paste should be reapplied every 2 to 3 years, but there are a few caveats to that statement. Your thermal paste should last longer than 3 years if:

  • Your PC only does light work, such as office work, web browsing, and media playback.
  • Your PC is kept cool and clean at all times, and never allowed to overheat.
  • You don’t use your computer for graphically-intense tasks, such as gaming.
  • When you do play games, they are small and have low graphics.
  • The thermal paste used was of a very high quality.

In the cases listed above, your thermal paste could last as long as 7 years, according to manufacturers. However, during the course of those years, you will want to do the occasional check to make sure the thermal paste is holding up. Bear in mind that the harder your computer works, the faster the thermal paste will dry out and need to be replaced. You can tell by the following signs whether your thermal paste might need to be reapplied:

  • Your computer is starting to overheat despite no changes in usage (this could also mean it is caked with dust and needs to be cleaned).
  • You can see flakes of dried thermal paste coming loose from between the CPU and the cooler.

You will also need to replace your thermal paste any time that you remove the cooler from the CPU. Whether you are doing this to check on the paste, upgrade either component, replace one of them, or simply to give your computer a thorough clean, you will need to clean all of the old thermal paste off both the CPU and cooler, and apply a fresh blob before installing or reinstalling the components.

Old Thermal Paste on CPU and Cooler
Old Thermal Paste on CPU and Cooler

Under no circumstances should you try to reuse old thermal paste, even if it has not dried out yet. There is a very high chance that in doing so, you would create air bubbles that would capture and hold hot air, causing your CPU to overheat. Always clean all the old thermal paste off completely (isopropyl alcohol swabs work wonders) and start fresh on a clean chip with new thermal paste.

How to Apply Thermal Paste

Step 1

As mentioned before, you should start by making sure both the cooler (unless brand new) and the CPU’s IHS are completely clean of old thermal paste. You can use isopropyl alcohol swabs or apply the alcohol to a lint-free swab or cloth yourself. Be sure to get into all the small corners and nooks and get all the old paste out. Never use any kind of scraper to remove the thermal paste, as you could cause serious damage to your CPU.

Step 2

Placing CPU Chip onto Motherboard

Once the components are clean of old paste, do not rush ahead to apply the fresh paste until you are absolutely ready. The thermal paste application should be the very last step before placing the cooling unit onto the CPU. So first, get everything ready, have the right tools at hand, and check the user manual for the cooler to ensure that you know exactly how to attach it to the mounting.

Step 3

There are a number of ways in which you can apply heat paste to your CPU, some of which are approved by various CPU manufacturers. We will discuss the “blob” or “pea” method here, but you can see from the following video that there is very little difference between the CPU temperature outcomes based on the method used.

Thermal paste application methods

Squeeze a pea-sized bead of thermal paste onto the middle of the CPU’s Integrated Heat Spreader. Using too much paste will cause it to squeeze out from between the cooler and CPU, and onto the motherboard. If this happens, you will have to start all over again by cleaning off both components, as well as any leakage. Using too little would mean insufficient coverage of the CPU, and could result in overheating.

Placing Thermal Paste on CPU

Although it may be tempting to spread the thermal paste yourself, and some people even recommend it, we don’t. Some tubes of thermal paste come with spreaders, but if you do this job incorrectly, you could leave air bubbles that will cause overheating in future.

Step 4

Place the cooling unit onto the CPU, using the mounting as a guide. Press down lightly to spread the thermal paste between the components, but without allowing the cooler to slide around. If you press too hard, you could cause damage to the motherboard or CPU, but pressing too lightly could allow the cooler to slide, leaking heat paste onto the motherboard.

Step 5

Hold the cooler in place while you tighten it onto the mounting. Work diagonally, starting with one corner and then moving to the opposite corner. Do not tighten the screws completely right away – rather loosely attach each one, and then tighten them each an equal amount in stages, until they are all completely tight, still working in diagonals.

Step 6

Make sure there are no thermal paste leaks*, ensure that the cooler is tightly fastened, and replace any components you may have had to remove to get to the CPU or create space for a new cooler. Then plug in and turn on your PC, and check that everything is working 100%.

*Note: if there is any thermal paste leaking out from the CPU, you will have to remove the cooler and CPU and start again, as you have used too much thermal paste. Do not try to reuse this paste – you will need to clean it all off of both components, as well as the motherboard or CPU mounting, and use a fresh application.

If you would prefer this tutorial in a video format, this video is very informative.

Amy Catchpole

Amy is a staff writer at Durability Matters.

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