Desktop hardware

CPU overheating

A CPU running hotter than it should is most often due to dried-out thermal paste, a poorly mounted cooler, or dust, all of which are fixable without new hardware.

Difficulty
Moderate
Time
45–90 minutes
DIY cost
$5–$60
Pro cost
$80–$180

Symptoms

  • CPU temperatures above roughly 80–90C under load, depending on the model
  • System throttles performance or restarts under heavy use
  • Fans run loud trying to keep up with rising heat
  • Temperatures climbed gradually over months or years

Likely causes

  • CommonDried out or degraded thermal paste between the CPU and coolerPaste loses effectiveness over a few years, especially under heavy use.
  • CommonCPU cooler mounted incorrectly or not making full contactUneven mounting pressure creates hot spots the cooler can't manage.
  • CommonDust clogging the cooler's fins and fanReduced airflow through the heatsink directly raises temperatures.
  • PossibleCooler undersized for the CPU's power drawA stock or budget cooler may not be enough for a higher-end or overclocked CPU.
  • PossiblePoor overall case airflow trapping heat near the CPUEven a good cooler struggles in a case with insufficient airflow.

What to do

  1. Check CPU temperatures at idle and under load using monitoring software to establish a baseline.
  2. Clean dust from the CPU cooler's fins and fan with compressed air.
  3. If temperatures are still high, remove the cooler, clean off old thermal paste, and reapply a fresh, appropriately sized amount.
  4. Reseat the cooler evenly, following the mounting instructions for even pressure across all screws.
  5. Improve case airflow by adding or repositioning case fans if the whole case runs warm.
  6. If temperatures remain high with fresh paste and proper mounting, consider a more capable cooler for the CPU.

Tools and parts

  • Thermal paste
  • Compressed air
  • Screwdriver
CPU thermal pasteSearch: “CPU thermal paste”

When to call a pro

If CPU temperatures stay high after reseating the cooler with fresh paste and confirming good airflow, a repair shop can verify whether the cooler or CPU itself needs replacing.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.