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CPU Coolers: Applying Thermal Grease

How To: Properly Plan And Pick Parts For An Air-Cooled PC, Part 2
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Is There A Perfect Method?

Just as every BBQ fanatic claims to know how to grill a perfect steak, enthusiasts all have opinions on the best way to apply thermal compound. Do you spread it with a spatula, flatten it with a razor blade/credit card, use the one-fingered glove method, or merely apply a drop of paste in the middle of your processor? Heated forum discussions suggest that there is no such thing as the method. However, because this article is tailored to beginners, we want to focus on consistency and repeatability. Nobody wants to fry their CPU, anyway. After field tests with a couple of novices, we settled on the following:

A Drop Of Paste Method: Foolproof

By squeezing the tube, we put a small drop of paste right in the middle of the CPU. The correct quantity is about the size of a lentil (not a pea). Refer to the pictures below for the end result using different quantities of paste.

In order to take these pictures, we put an ultra-thin transparent film between the cooler base and the CPU. We installed and then uninstalled the cooler. The paste remained between the CPU heat spreader and transparent film. Thus, these pictures illustrate the paste spread just as if the cooler was invisible. Let’s take a look at the results when different quantities of thermal paste are used:

Quantity
After Paste Application
After Mounting the Cooler
Lower Limit (Minimum)

Upper Limit (Maximum)


It is important to install the cooler evenly and to push it down a little bit. Hooking the cooler in on one side and then tilting it into position will result in a lopsided spread. Screws should be tightened in a diagonally alternating way.

Sins, Mistakes, And A Brief Afterword

There are many methods that achieve similar results, when properly used. However, spreading the paste with a gloved finger seems problematic, as it would be difficult to suggest the proper quantity. Furthermore, just like the credit card method, this technique is too difficult and uncertain, as the thickness of the compound layer is tough to gauge without lots of experience.

Glove games. You can do this once you have a few years of experience and can estimate how thick the resulting paste layer really is. Beginners run the danger of becoming a pastry baker. That's a joke, by the way. Wait until you get to the last page.

Cheesecake? Way too much paste! Apart from the fact that everything oozes out and makes a big mess, the thermal conductance is negatively impacted and the cooler does not achieve its optimal performance.

Mister Scrooge. It’s OK to be frugal, but not when it comes to thermal paste. This is how people buttered their bread during the Great Depression. For a CPU, it’s not enough. When you can read the type and date code, the layer of compound is too thin.

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