How to Choose the Best Thermal Paste & Grease: Thermal Compound Recommendations

Thermal paste, also known as thermal grease or heat sink compound, is a substance applied between heat-generating components like CPUs and other types of processors and their heat sinks. Its role is to fill the microscopic air gaps that would otherwise create a barrier to efficient heat transfer, thereby ensuring optimal heat dissipation. Effective thermal management is crucial because even slight temperature increases can significantly reduce the lifespan and performance of electronic components.

Choosing the right thermal paste is essential for maintaining optimal operating temperatures, especially in demanding applications like high-performance gaming PCs, intensive workstations, and industrial machinery where thermal stress can lead to system failures.

This guide will provide a clear breakdown of the key considerations when choosing thermal pastes, such as thermal conductivity, viscosity, and compatibility, so you can make an informed decision on the best thermal cooling paste for you.

Selecting the right thermal compound paste involves evaluating several key factors to ensure optimal performance and compatibility with your specific application. Whether you're building a high-end gaming rig or maintaining industrial equipment, understanding these considerations will help you make an informed decision. For a breakdown of recommended products, jump to "Best Thermal Paste and Thermal Grease", or continue reading for a detailed look at the factors to consider.

• Thermal Conductivity (W/mK): Measured in Watts per meter-Kelvin (W/mK), thermal conductivity indicates the paste's ability to transfer heat. A higher W/mK rating signifies a greater capacity to conduct heat away from the component, resulting in lower operating temperatures and improved system stability, especially under heavy loads. This is a crucial metric for high-performance applications where efficient cooling is paramount. In industrial settings, where components may operate under continuous stress, a high W/mK rating is essential for maintaining consistent performance. To learn more about electrical measurements, read our blog post on the difference between watts and volts.
• Viscosity & Application Ease: Viscosity refers to a fluid's resistance to flow. In thermal paste, it dictates how easily the compound spreads across the component's surface. Lower viscosity pastes flow readily, making them simpler to apply and ideal for users who are new to thermal paste application. Higher viscosity pastes, while potentially more challenging to spread evenly, often provide better long-term stability and resistance to pump-out (the gradual displacement of paste due to thermal cycling), making them good options for professionals seeking sustained performance.
• Curing Time & Longevity: Consider both curing time and longevity when selecting thermal paste. Some pastes offer immediate peak performance, ideal for quick testing, while others require a curing period for stability. Longevity, the paste's effective lifespan, is equally important. Match these characteristics to your application's requirements for optimal results. In mission-critical systems, a long-lasting, stable thermal paste can minimise maintenance and downtime.
• Electrical Conductivity & Safety: Certain thermal pastes, particularly liquid metal varieties, are electrically conductive, offering superior thermal transfer. However, this conductivity poses a risk of short circuits if not applied meticulously. Consequently, these pastes are best suited for experienced users. For those new to thermal paste application, or in scenarios where safety is a primary concern, non-conductive pastes are the recommended choice.
• Compatibility with CPU/GPU/Other Components: Ensuring compatibility between your thermal paste and components is paramount. Certain pastes, like liquid metal compounds, can react negatively with specific materials. For instance, aluminium, often used in heat sinks, can corrode when in contact with liquid metal. Standard pastes, formulated with silicone or ceramic, offer wider compatibility. Therefore, reviewing the specifications of both your processors or components and the chosen thermal paste is essential to prevent damage.
• Price vs. Performance: The cost of thermal compounds can vary significantly. While high-end options promise the best possible thermal performance, it's important to consider if that level of performance is necessary for your application. Many affordable pastes offer excellent heat transfer capabilities and represent a wise investment for most users.

Follow these recommended tips when applying thermal paste on a CPU for your safety and the best performance:

• Use Gloves: Wear nitrile or latex gloves to prevent skin contact with thermal paste and avoid potential irritation.
• Clean the CPU and Heat Sink Surface: Before application, use isopropyl alcohol and a lint-free cloth to ensure the CPU and heat sink surfaces are clean and free of debris. A clean surface will allow for optimal thermal contact and the best results.
• Avoid Applying too Much: You only need to apply a small, pea-sized amount of thermal paste. A thin, even layer is ideal for optimal heat transfer. Using too much thermal paste can cause excess paste to ooze out and potentially cause issues.
• Keep Thermal Paste Away from Motherboard Components: Good thermal compounds are excellent electrical conductors. While this makes them excel at heat transfer away from the CPU, the same properties can cause short circuits if the thermal paste comes into contact with sensitive motherboard components.

Choosing the right thermal paste or thermal grease is critical for maintaining the optimal operating temperature and performance of your electronic components. Whether you're building a high-performance gaming rig, a professional workstation, or working with industrial equipment, selecting the appropriate thermal compound ensures efficient heat dissipation and prevents overheating. RS Australia is a reliable source for a diverse range of high-quality thermal management solutions from leading brands, providing the products and support you need to keep your systems running smoothly. Remember to carefully assess your specific needs, considering factors like thermal conductivity, application ease, and safety, to make an informed decision and achieve the best results.

Tip: After applying thermal paste and reassembling your system, use a fluke multimeter to test the electrical continuity and ensure all connections are secure. This step is particularly important when working with sensitive electronic components or high-power systems. This is a crucial step in ensuring the safe and effective operation of your system.