I upgraded to a Ryzen 7 5800X3D and paired it with a Thermalright AXP120-X67 low-profile cooler. The processor sits around 75°C at idle, then quickly reaches 90°C and begins thermal throttling under load. Is this mainly because the cooler is too small, or could there be an installation, thermal paste, or airflow problem?
2 Answers
Check the basics while replacing or remounting it: make sure the protective film is removed, the thermal paste is applied properly, and the cooler is sitting flat with even mounting pressure. Also verify that the fan is spinning correctly and that the case has reasonable intake and exhaust airflow. However, 75°C idle and immediate throttling strongly suggest the low-profile cooler is simply being overloaded rather than just having a minor contact issue.
The 5800X3D is expected to run warmer than many other processors, but it should still be paired with a substantial cooler. After installing a larger air cooler or a decent liquid cooler, you can use PBO Curve Optimizer or another undervolt to reduce voltage and temperatures. Adjusting the fan curve and improving case airflow can help too, but undervolting should be treated as an extra step, not a replacement for adequate cooling.
Good contact can help, but it cannot turn a small SFF cooler into a suitable high-capacity cooler. If the mounting looks correct, upgrading the heatsink is the practical solution.