How to apply thermal paste

What is Thermal Paste and Why is it Important?

Thermal paste, also known as thermal compound or thermal grease, is a thermally conductive material that is applied as an interface between a heat-generating electronic component, such as a CPU or GPU, and a heatsink. Its primary purpose is to fill in microscopic imperfections on the surfaces of both the component and the heatsink. These imperfections, invisible to the naked eye, can create air gaps. Air is a poor conductor of heat, so these gaps significantly impede the efficient transfer of heat away from the component. By filling these gaps, thermal paste creates a continuous thermal bridge, allowing heat to flow much more effectively from the hot component to the cooler heatsink, which then dissipates the heat into the surrounding environment.

When Should You Apply Thermal Paste?

Thermal paste needs to be applied whenever a heatsink is removed from a component or when a new component is installed. This typically occurs during:

• Initial PC Building: When assembling a new computer.
• Heatsink Replacement or Cleaning: If you upgrade your heatsink, need to clean dust buildup from an existing one, or troubleshoot overheating issues.
• Component Replacement: When replacing a CPU or GPU.
• Overheating Issues: If you notice your component is running hotter than usual, reapplying thermal paste can often resolve the problem.

The lifespan of thermal paste can vary. While some pastes are designed to last for many years, others may degrade faster. It's generally recommended to reapply thermal paste every 3-5 years as a preventative measure, or sooner if you experience significant temperature increases.

Preparing for Application

Before you can apply new thermal paste, proper preparation is essential for optimal performance and longevity.

Cleaning the Surfaces:

You must thoroughly clean both the surface of the CPU (or GPU) and the contact plate of the heatsink. Old thermal paste, dust, and any residue can interfere with the new paste's ability to create a good thermal bond.

• Materials Needed: High-percentage (90% or higher) isopropyl alcohol and lint-free cloths (like microfiber cloths or coffee filters). Avoid paper towels, as they can leave behind lint.
• Cleaning Process: Apply a small amount of isopropyl alcohol to the lint-free cloth. Gently wipe the surface of the CPU lid and the heatsink's contact plate until all residue is removed and the surfaces are clean and dry. Ensure the surfaces are completely dry before proceeding.

Gathering Your Tools:

You'll need:

• New thermal paste.
• Isopropyl alcohol (90%+) and lint-free cloths for cleaning.
• A small, flat-edged tool (like a plastic spreader, credit card edge, or even the applicator that comes with the paste) if you choose a spreading method.
• Gloves (optional, to keep paste off your skin and skin oils off the components).

Methods of Applying Thermal Paste

There are several accepted methods for applying thermal paste, each with its proponents. The key is to achieve an even spread without air bubbles or excess paste.

1. The Pea-Sized Dot Method (Most Common & Recommended):

This is the simplest and often most effective method for most CPUs and GPUs. The pressure from the heatsink will spread the paste.

1. Dispense: Place a single, small dot of thermal paste, roughly the size of a small pea or a grain of rice, directly in the center of the CPU's integrated heat spreader (IHS) – the metal lid of the CPU.
2. Mount Heatsink: Carefully align and place the heatsink directly onto the CPU. Ensure it is seated correctly.
3. Secure Heatsink: Gently press down and secure the heatsink according to its mounting mechanism (screws, clips, etc.). Tighten screws in a diagonal pattern, a little at a time, to ensure even pressure. The pressure from mounting the heatsink will spread the paste outwards.

2. The Line Method:

This method is often recommended for rectangular CPUs or larger components.

1. Dispense: Apply a thin line of thermal paste vertically or horizontally across the center of the CPU. The length of the line should be about 30-50% of the CPU's width.
2. Mount & Secure: Mount and secure the heatsink as described in the pea-sized dot method.

3. The Spread Method (Use with Caution):

This method involves manually spreading the paste evenly before mounting the heatsink. It requires a delicate touch to avoid introducing air bubbles.

1. Dispense: Apply a small amount of paste to the center of the CPU.
2. Spread: Using a provided spreader, a plastic card, or a gloved finger, gently spread the paste into a thin, even layer across the entire surface of the CPU's IHS. Aim for a layer just thick enough to cover the surface without being excessive.
3. Mount & Secure: Carefully mount and secure the heatsink.

How Much Thermal Paste Should You Use?

The amount of thermal paste is critical. Too little will leave air gaps, and too much can squeeze out from under the heatsink, potentially causing a mess or even shorting out nearby components on the motherboard. The general rule of thumb is to use just enough to cover the surface area when the heatsink is applied. For most standard CPUs, a pea-sized dot is sufficient. For larger or rectangular CPUs, a slightly larger dot or a thin line might be more appropriate. Always refer to the thermal paste manufacturer's instructions, as they may have specific recommendations for their product.

Post-Application Checks

After applying the thermal paste and mounting the heatsink, it's important to perform a few checks:

• Stability: Ensure the heatsink is firmly secured and does not wobble.
• Boot Up: Turn on your computer and monitor the CPU temperatures using monitoring software (like HWMonitor, Core Temp, or your motherboard's utility).
• Temperature Monitoring: Idle temperatures should be relatively low (e.g., 30-50°C, depending on the CPU and ambient temperature). Under load (running a demanding application or benchmark), temperatures should remain within safe operating limits (generally below 85°C for most CPUs, consult your CPU's specifications).
• Re-application: If temperatures are still too high, you may need to reapply the thermal paste, ensuring you followed the cleaning and application steps correctly. Check that the heatsink is making even contact.

By following these steps, you can ensure your components are properly cooled, leading to better performance and a longer lifespan.