Computer processors generate a considerable amount of heat during operation. If this heat isn’t properly dissipated, performance drops, system stability decreases, and hardware lifespan shortens. To ensure effective heat transfer between the CPU and its cooler, thermal paste is used. However, applying too much or too little paste can reduce cooling efficiency. In this guide, we explain thermal paste types, the correct way to apply them, and when they should be replaced.
Thermal paste types and their properties
Thermal pastes are generally divided into three categories: ceramic, metal-based, and carbon-based compounds. Each has distinct advantages depending on usage and experience level.
Ceramic-based pastes are the safest and most affordable option. Since they are non-conductive, there is no risk of short circuits even if a small amount spreads beyond the CPU surface. Their thermal conductivity is lower compared to other types but sufficient for daily use. They are easy to apply, clean, and ideal for beginner users.
Metal-based pastes contain materials like silver, aluminum, or liquid metal. These deliver the best thermal performance but must be handled with care because they conduct electricity. Improper application may cause a short circuit on the motherboard. They are best suited for experienced users who seek maximum cooling efficiency.
Carbon-based pastes provide a balance between safety and performance. They are long-lasting, resistant to drying, and maintain consistent heat transfer over time. These characteristics make them a reliable choice for gaming PCs and professional systems that run at high temperatures for long periods.
Preparing the CPU and cooler
Before applying new paste, all traces of the old one must be cleaned. Any residue left on the surface prevents proper heat transfer. Use isopropyl alcohol (90% or higher) and a lint-free microfiber cloth for this process.
Turn off the computer, unplug it, and remove the cooler carefully. Clean both the processor and the cooler base until they are smooth and dry. Avoid using paper towels as they may leave fibers behind. Before continuing, touch a metal surface to discharge any static electricity.
How to apply thermal paste
The amount of paste used is crucial. Too little won’t cover the entire surface, while too much can act as an insulator instead of a conductor.
Dot method
Place a pea-sized drop of paste in the center of the CPU. When the cooler is mounted, the paste spreads evenly across the surface due to pressure. This is the most commonly used and safest method.
Line method
Apply a thin, straight line of paste along the center of rectangular CPUs. Once the cooler is installed, the paste spreads across the full area. This technique works well for Intel processors with long heat spreaders.
Spread method
Use a small spatula or applicator to spread the paste evenly across the CPU surface. While this method provides full coverage, it requires precision. Uneven spreading can lead to air pockets that reduce heat transfer. After applying the paste, align the cooler on top of the CPU and tighten the screws diagonally. This ensures even pressure and optimal contact between the surfaces.
Checking temperatures after installation
Once the cooler is in place, turn on the computer and monitor the temperatures using HWMonitor, CoreTemp, or MSI Afterburner. At idle, normal temperatures should range between 30–45°C. Under heavy load, temperatures between 70–85°C are acceptable depending on the cooler type. If temperatures are higher, check whether the cooler is mounted properly or if too much paste has been used.
When to replace thermal paste
Thermal paste degrades and dries out over time, reducing its ability to conduct heat. The general replacement interval is every 2 to 3 years, though this can vary depending on the system’s workload and environmental conditions.
If the CPU temperature suddenly rises, the fan runs louder, or you notice visible cracks on the paste, it’s time for reapplication. Regular maintenance ensures the processor stays cool, runs efficiently, and extends the system’s overall lifespan.
