How to replace thermal paste on a CPU and GPU: when and how

Thermal paste fills microscopic gaps between the processor (or graphics chip) and the cooler so heat moves into the heatsink. Over the years it dries out and cools worse. A fresh layer can lower temperatures by several degrees up to 10–15 °C on an old PC.

1. When to replace it

• CPU: usually every 3–5 years, or when you remove the cooler for any reason.
• Graphics card: every 2–4 years, or when the GPU hot spot and temperature have grown under the same load.
• Signs: temperatures rise even though the PC is clean (dust is cleaned already), fans spin up fast at idle, the CPU reaches 90 °C+ in games, performance drops because of throttling.

Warranty: removing a CPU cooler does not affect the warranty. A graphics card is different: on many models a sticker on a screw or a manufacturer policy means disassembly voids the warranty. Check before you start, especially on a card that is still covered.

2. What you need

• Thermal paste. Reliable choices: Arctic MX-4 / MX-6, Noctua NT-H1 / NT-H2, Thermal Grizzly Kryonaut. A small tube is enough for several uses.
• Isopropyl alcohol 90%+.
• Lint-free wipes or coffee filters (not cotton wool, it leaves fibres).
• A screwdriver set that fits your cooler. For a graphics card also a small Torx/Phillips set.
• For a graphics card: thermal pads of the same thickness as the originals (check the model’s teardown guide).

Do not use liquid metal if you are not experienced. It conducts electricity and can short the board, and it must never touch aluminium.

3. Processor: step by step

1. Warm up the PC for 5 minutes under light load. Warm paste is softer and the cooler comes off more easily.
2. Shut down, switch off the power supply, unplug the cable and press the power button for 5 seconds.
3. Take off the cooler. Unplug the fan cable, undo the screws or clips evenly (crosswise) and gently twist the cooler a few degrees to break the paste seal before lifting it straight up. Never pull it hard: a processor may come out of the socket together with the cooler, especially an older AMD one.
4. Clean the old paste from the processor lid and from the cooler base with a wipe and a few drops of alcohol. The surfaces should be clean and dry. Do not touch the contacts or pins with the alcohol.
5. Apply new paste. Put one pea-sized dot (about the size of a grain of rice for small chips) in the centre of the processor lid. Do not spread it: the cooler pressure will do it. Large CPUs (for example Threadripper) need a thin cross or a few lines.
6. Remove the protective film from the cooler base if it has one. This is a very common mistake.
7. Mount the cooler straight down without sliding it sideways, and tighten the screws evenly, crosswise, a little at a time.
8. Connect the fan cable to the CPU_FAN header and close the case.

4. Graphics card: what is different

1. Find a guide for your exact model. Coolers differ a lot between brands and models.
2. Take photos at each step and keep screws sorted by place (they are often different lengths).
3. Remove the cooler gently, unplug the fan and LED cables.
4. Clean the old paste from the chip and the cooler plate. Check the thermal pads on the memory and VRM: if they are torn, hard or oily, replace them with pads of the same thickness.
5. Apply paste on the GPU chip (a small dot or a thin even layer), mount the cooler and tighten the screws crosswise, gradually.

5. Check the result

• Start the PC and check that all fans spin.
• Run a stress test or a game for 15–20 minutes and watch the temperatures in HWiNFO or MSI Afterburner. Compare with the values before the replacement.
• If the temperature is worse than before, the cooler is probably not seated flat or the film was left on. Reinstall it.

6. Common mistakes

• Too much paste. It does not improve cooling and can spill onto the contacts.
• Reusing old paste or mixing different pastes without cleaning.
• Uneven screw tightening.
• Forgetting to connect the fan cable.
• Touching pins or pads with fingers.