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 the cooler simply too small for this CPU, or should I check the mounting, thermal paste, case airflow, or other installation issues?
4 Answers
An AIO such as the Arctic Liquid Freezer III would handle the CPU comfortably, but it is overkill if your case supports a good dual-tower air cooler. A quality two-tower heatsink with two fans is usually the simpler and cheaper solution.
The AXP120-X67 is mainly intended for compact small-form-factor systems, and it is likely being overwhelmed by the 5800X3D. This chip can run warm because of its stacked-cache design, so a larger dual-tower air cooler—such as a Phantom Spirit-class cooler—would be a much better match. A liquid cooler can also work, but it is probably unnecessary unless your case requires it.
Those temperatures are high enough that I would also verify the basics: make sure the cooler is mounted evenly, the contact plate is flat against the CPU, there is a sensible amount of thermal paste, and no protective film was left on the cooler. Check case airflow and the fan curve too. However, even with perfect contact, this low-profile cooler may simply lack the capacity needed for sustained loads.
Once you install a larger cooler, try a mild PBO undervolt or reduced power limit. The 5800X3D often responds well to this and can run cooler without sacrificing much performance. Repasting with a good compound may help, but it will not compensate for an undersized heatsink.
That makes sense. I probably should not have relied on an automated cooler recommendation without checking how well it handles this particular CPU.