What have your long-term experiences been with Arctic MX-4 or MX-6 thermal paste? Have temperatures increased after one, two, or three years on CPUs such as the Ryzen 7 7800X3D, Ryzen 7 9800X3D, or comparable Intel chips? My 9800X3D uses MX-4 with a Thermalright Phantom Spirit 120 SE. After about a year, Cinebench R23 temperatures increased by roughly 6°C, despite testing with the same BIOS defaults, BIOS version, ambient temperature, and hardware. Could this be pump-out from the CPU heat spreader, or is the change more likely normal testing variation?
4 Answers
Most thermal pastes remain usable for years, and many people never replace them before upgrading their system. A 6°C difference could still come from small changes in testing conditions, dust, fan behavior, mounting pressure, or other variables. If the temperatures are still within a safe range, it may not indicate a real problem. MX-4 has also remained usable for many years across repeated applications.
I used MX-6 on a Ryzen 9 5950X for about two years. When I removed the cooler, the paste still looked nearly as fresh as it did when it was applied, and I did not see obvious signs of it drying out or separating.
Pump-out can happen with some pastes, and MX-6 or newer formulas may show it more strongly in certain setups. I saw visible pump-out after roughly six months in a compact gaming device, so I switched to a phase-change thermal pad instead. Results can vary depending on the CPU, cooler pressure, and mounting pattern.
A quality paste should generally last around five years under normal use. If you want to avoid changes caused by paste movement, a phase-change pad such as a KryoSheet-style product is another option.
I tested both times with BIOS defaults, the same BIOS version, the same system, and the same ambient temperature, so I suspect the paste or mounting may be responsible.