How much thermal paste should I use?

There’s a lot to keep in mind when building a PC. You have to make sure all the components will work together, plug the correct connectors into the right sockets, which can be particularly annoying when it comes to the tiny pins found in the connectors on the front I/O cables.

At some point during your PC building adventure you will need to affix the cooler to the CPU. The scary bit of actually installing the CPU into the socket on the motherboard has come and gone, with just the finishing touches still to be made.

Before clamping the cooler on top of the CPU though, you must first apply some thermal paste to the CPU. This is vital. The CPU will overheat without thermal paste between it and the cooler, but how much do you use? Too much and the pressure from the cooler will squeeze it out, making it leak all around the CPU socket. Too little and you won’t have optimal heat transfer from the CPU to the cooler, which will negatively affect your PC's performance, as the CPU will thermal throttle more quickly.

This is one of those things that PC gaming nerds have been debating for decades at this point, however, there are no hidden methods here. It’s super simple. Your CPU and cooler will work perfectly with the application of a pea-sized amount of thermal paste deposited directly onto the middle of the CPU. After this, the pressure from securing the cooler will disperse the thermal paste evenly over the surface of the CPU, ensuring optimal thermal transfer from the CPU to the cooler.

It’s worth noting here that everything said in this article applies whether you’re using an AIO cooler, such as our iCUE LINK H150i LCD AIO, an air cooler, or the CPU block in your custom cooling loop. None of these need any more or less thermal paste. Additionally, our AIO coolers come with thermal paste pre-applied, so you only need to worry about it if you're re-installing the cooler a second time.

If you do need some thermal paste, our CORSAIR XTM70 Extreme Performance Thermal Paste is capable of transferring the heat from even the most fiery CPUs with ease. Additionally, it comes with an application stencil kit, which pre-spreads the thermal paste, removing the potential for error that could come as a result of incorrect cooler installation.

If you’re after a visual example, our resident Funny TikTok Man, Nick, has posted a video showing you how much thermal paste to use and how to apply it that you can find below.

It’s a good question. After all, we’re trying to transfer heat from the CPU to the cooler as efficiently as possible, so why put something in between those two things? Surely that just gets in the way?

Well, in a perfect world, you’d be right. In a perfect world the surface on the top of the CPU heat spreader and the surface of the cooler would be perfectly flat, as in flat down to the last atom. In this world, the cooler and the CPU would have perfect contact and thus, truly optimal heat transfer.

Of course we don’t live in a perfect world, and when you take it down to the microscopic level, even the bleeding edge tools and techniques used to machine CPUs and coolers do not result in perfectly flat parts. So, if you were to put those two parts together there would be tiny little gaps, invisible to the human eye, but significant enough to cause problems.

These problems arise because air will occupy this gap, and air is a really poor conductor of heat and not nearly good enough for the purpose of cooling a CPU. This means that the gaps must be filled, and the air removed. Remembering that we can’t machine parts flat enough to completely eliminate gaps, we arrive at thermal paste for our solution.

Thermal paste is simply a compound that can flow enough to be pressed into the gaps to fill them and it's conductive so it can facilitate heat transfer between the CPU and the cooler. This is one of the reasons that installing a cooler requires you to wrench it down worryingly tight. This pressure is necessary to squish the thermal paste into those gaps and force the air out.