Why Is My CPU Overheating? Causes and Fixes

If you are asking why is my CPU overheating, start with the temperature: a CPU that idles above 50°C or hits 95°C under load is running too hot, and the cause is usually dust, a bad cooler, old thermal paste or poor airflow. The fix is almost always simple — and it starts with finding out what is actually hot, and why.

What is overheating, exactly?

A CPU is overheating when it gets hot enough to slow itself down, which is called throttling, or to shut the PC down. Most chips start throttling at around 95–100°C, and they shut down above that. A healthy desktop CPU idles at 30–45°C and stays under 85°C under full load. Our how long a desktop CPU lasts guide explains what heat does over time, and our how to benchmark your CPU guide shows you how to measure the temperature while the chip is working.

Cause 1: dust in the cooler and the case

Dust is the most common cause of overheating, and the easiest to fix. Dust clogs the fins of the cooler, blocks the intake filters and slows the fans. Clean the cooler and the case with compressed air, holding the fans still while you blow them out, and clean the dust filters. Do this every few months, and more often if you have pets. A dusty cooler can add 10–20°C to your temperature — and our CPU cooling basics guide explains how a cooler works, and why airflow matters.

Cause 2: the cooler is too small or badly mounted

If the cooler is too small for the chip, it will overheat under load no matter how clean it is. A 14900K on a stock cooler will throttle; a Ryzen 7 9700X on a mid-range air cooler will not. A cooler that is not mounted evenly — one screw tighter than the others — also overheats, because only part of the CPU touches the cooler. Our how to choose the right CPU cooler guide helps you match the cooler to the chip, and our best CPU cooler for gaming guide lists the best options.

Cause 3: old or badly applied thermal paste

Thermal paste dries out over time, and dry paste conducts heat badly. If your temperatures have crept up over the years, old paste is a likely cause — and it is cheap to fix. A bad application is just as bad: too little paste leaves dry patches, and too much squeezes out the sides. Our how to apply thermal paste correctly guide shows the pea-sized dot method, which is all you need.

Cause 4: poor case airflow

Poor case airflow is a common cause, especially in cases with a solid front panel or with the fans installed the wrong way round. Hot air has to leave the case, and cool air has to come in — if the fans are fighting each other, the hot air stays inside and the CPU cooks. Check that the front fans pull air in and the rear and top fans push it out, and make sure cables are not blocking the airflow. Our CPU cooling basics guide covers the airflow basics.

Cause 5: a hot chip pushed too far

Sometimes the chip itself is the problem: an overclock with too much voltage, or a chip that is simply very hot by design, such as a 14900K. Our how to fix an unstable overclock guide shows how to step back to stable settings, and our overclocking basics guide explains why voltage is what creates the heat. If the PC is a laptop, the cause is usually the same — dust and old paste — but the fix is harder, so see our best laptop CPU for battery life guide for the laptop side.

How to check and fix it — a quick checklist

• Check the temperature with a monitoring tool, at idle and under load.
• Clean the dust out of the cooler, the fans and the filters.
• Check that the cooler is mounted evenly and the fan is spinning.
• Replace the thermal paste if it is more than two or three years old.
• Check the case airflow — front fans in, rear and top fans out.
• Step back any overclock and check the temperature again.

The bottom line

An overheating CPU is almost always fixed by cleaning, a better cooler, fresh thermal paste or better airflow — not by buying a new chip. Work through the checklist above, and check the temperature after each step. Browse our cooling guides and our troubleshooting guides for the next steps.