The Best Thermal Paste for a CPU? Test and Ranking
Everyone upgrading their computer sooner or later faces the question: which thermal paste should I choose to keep my system stable and safe for years? It’s not an easy decision – dozens of products are available on the market, and popular brands compete with slogans like “highest performance” or “innovative formula.” In practice, however, it’s hard to verify which of these claims are true. That’s why buying a good thermal paste requires an understanding of which solution will work best in a specific application.
It’s worth taking a closer look at how different types of pastes compare. Classic “metal-based pastes” behave differently than ceramic, diamond, or silicone ones. Each type has its advantages and limitations, and the choice of the best thermal paste should depend on the purpose of the computer. In gaming setups and for overclocking, excellent thermal conductivity is the most important factor, which is why premium products matter most. In office PCs, good thermal conductivity combined with an affordable price – offered by simpler thermal pastes – is often enough.
You also can’t forget about maintenance. Replacement intervals depend on product quality. High-quality pastes maintain stable thermal conductivity for many years. Lower-quality products dry out quickly – sometimes after just a few months – which reduces their effectiveness. In such cases, frequent replacement becomes necessary.
In this article, we’ll present not only test results but also a ranking of the best thermal pastes, so everyone can find the answer to the question: which thermal paste should I buy to ensure real effectiveness?
Why are thermal pastes so important?
Modern processors generate massive amounts of heat. Even the best CPU cooler won’t be effective without a thin layer of thermal paste. This paste fills micro-gaps between the processor and the heatsink, allowing heat transfer far more efficiently than metal-to-metal contact alone.
In practice, paste can lower temperatures by several degrees, improving performance, stability, and the lifespan of your computer. The ideal thermal paste means not only a cooler CPU but also reduced risk of failure and better protection of your investment in expensive components.
Types of thermal pastes and their composition
The market offers a wide variety of pastes, but not all are suitable for PCs:
Metal-based thermal paste – contains particles of metals (copper, silver, gold). Works best with heat-conductive heatsinks, e.g. copper (e.g. AG Copper Paste).
Ceramic thermal paste – safe, versatile, and durable.
Diamond thermal paste – highly efficient, transfers heat effectively, and does not conduct electricity.
Silicone thermal paste – the cheapest category. Safe (non-conductive) but provides the weakest cooling. Best for simple devices like portable fridges, household appliances, or low-power electronics.
Thermal conductivity isn’t everything
The choice of the best thermal paste should rely on four pillars:
Thermal conductivity – measured in W/mK. Higher values mean better cooling.
Paste composition – determines safety and durability (metal, silicone, ceramic, diamond).
Optimal density – affects ease of application. Too thick = hard to apply, too runny = may spill outside. The ideal consistency ensures smooth, even spreading.
Durability – in gaming PCs or servers, replacing paste every 1–2 years is standard, but in office PCs the interval is 3–4 years. Over time, conductivity decreases, so regular replacement is key for stable temps and reliability.
If you’re looking for a good paste, don’t rely only on advertising. Look at test results and technical parameters.
How to apply thermal paste?
Even the best paste won’t help if applied incorrectly. Key rules:
Thoroughly clean the CPU and heatsink with isopropyl alcohol.
Apply a small amount – too much acts as insulation, not conduction.
Choose your method: dot, cross, or spreading with a spatula. In the next post, we’ll compare these methods.
Mount the cooler evenly, tightening screws in a cross pattern so the paste spreads uniformly.
Only correct application ensures effective cooling from the very first minutes of operation.
The Best Thermal Pastes – 2025 Ranking
We tested with an Intel i7-14700K CPU capped at 200 W. All pastes were applied identically to eliminate application errors.
The test also included popular, highly recommended products, often praised by reviewers and users. We intentionally avoid naming them – our focus is on technical parameters: conductivity, durability, and ease of application. This way, evaluation is based solely on actual properties, not branding.
Test procedure:
Stage 1 – Heating: 30 minutes Prime95 (small FFT’s) for thermal stabilization.
Stage 2 – Idle: 10 minutes, to assess cooling rate.
Stage 3 – Load: 20 minutes under load, measuring temps.
Analysis included:
Maximum and average CPU temps,
Delta (Δ) vs ambient temperature, to exclude environmental bias.
This reflected real PC usage – from full load to partial idle – showing how pastes perform under changing conditions.
Test Results – Best Thermal Paste
| No. | Thermal Paste | Thermal Conductivity (W/mK) | Density | Max Temp | Avg Temp | Δ max | Δ avg |
|---|---|---|---|---|---|---|---|
| 1 | Carbon Paste | 15.2 | 2.64 g/cm³ | 98°C | 78°C | 70.6 | 50.6 |
| 2 | Paste 12.8 W/mK | 12.8 | X | 100°C | 79°C | 72.4 | 51.6 |
| 3 | AG eXtreme | 6.0 | 2.38 g/cm³ | 100°C | 79°C | 73.8 | 51.8 |
| 4 | Paste 12.5 W/mK | 12.5 | 3.7 g/cm³ | 101°C | 78°C | 74.0 | 52.0 |
| 5 | Paste X | X | 2.6 g/cm³ | 100°C | 79°C | 73.0 | 52.0 |
| 6 | Stock CPU Paste | X | X | 100°C | 79°C | 68.4 | 53.4 |
| 7 | Paste 12 W/mK | 12.0 | 2.6 g/cm³ | 100°C | 81°C | 73.5 | 54.5 |
| 8 | Paste 4 W/mK | 4.0 | 2.5 g/cm³ | 101°C | 82°C | 74.0 | 55.0 |
| 9 | Paste H2 | 0.88 | 2.7 g/cm³ | 100°C | 86°C | 73.0 | 59.0 |
| 10 | Paste HPX | 2.8 | 2.0 g/cm³ | 100°C | 87°C | 72.0 | 59.0 |
| 11 | Paste HP | 1.5 | 2.1 g/cm³ | 101°C | 87°C | 74.0 | 60.0 |
| 12 | AG Silver | 3.8 | 2.37 g/cm³ | 101°C | 87°C | 74.0 | 60.0 |
| 13 | AG Gold | 3.57 | 2.35 g/cm³ | 101°C | 88°C | 73.8 | 60.8 |
| 14 | Paste H | 0.88 | 2.58 g/cm³ | 101°C | 86°C | 77.0 | 61.0 |
| 15 | Paste H3 | 0.88 | 1.37 g/cm³ | 101°C | 98°C | 74.3 | 71.3 |
Recommended Thermal Pastes – Summary
Best Thermal Paste – Carbon (15.2 W/mK): lowest Δ avg (50.6°C) + long durability = premium product.
Good conductivity – 12.5 and 12.8 W/mK pastes: stable CPU cooling, proving good thermal paste is a solid investment.
Mid-range – AG eXtreme: reliable for everyday PCs, easy to apply, optimal cooling.
Silicone pastes – H, H2, H3, HP, HPX: not suitable for PCs. The lowest density (H3) allowed CPU to hit 98°C, showing how critical efficient pastes are. Better suited for simple, low-load devices.
Thermal Paste for Demanding Applications
Gaming PCs, workstations, and servers demand premium solutions. High conductivity, stability, and durability are essential for reliable cooling under heavy loads.
Best Thermal Paste – Final Thoughts
When choosing a good thermal paste, don’t just look at W/mK. Composition, density, and durability matter equally. Together, they determine whether the paste really lowers temperatures and ensures system stability.
The best thermal pastes: Carbon, any product above 12 W/mK, and AG eXtreme.
Budget pastes (silicone-based): suitable only for simple electronics, like portable fridges, home appliances, or low-heat systems.
Below you’ll find a video of the tests, and you can read more about Thermal Conductivity at this link.