Laptop or Desktop Overheating
How to diagnose and fix a computer that is running hot or thermal throttling
A computer that runs hot is not always a problem — under heavy load, high temperatures are normal. It becomes a problem when the system thermal throttles (deliberately slows down the CPU to reduce heat), shuts down unexpectedly, or stays hot at idle.
The first thing to check is whether a runaway process is eating CPU for no reason. After that, it is usually a physical issue: blocked vents, dust buildup, or poor airflow. You can test your CPU performance and see if it is throttling at thetest.com/cpu.
- Open Activity Monitor — press Cmd + Space, type
Activity Monitor, and press Return - Click the CPU tab and sort by % CPU (click the column header). Look for anything using a sustained high percentage. Common culprits include browser tabs, video calls, Spotlight indexing (
mds_stores), and software update processes - If a process is stuck at high CPU and should not be, select it and click the X button in the toolbar to force quit it
- Check if
kernel_taskis using a lot of CPU. This is macOS deliberately throttling your CPU to bring temperatures down — it means the Mac is already too hot and protecting itself. Addressing the root cause (blocked vents, heavy workload, hot environment) is the fix - Close your Mac's lid slightly to check that the vents along the hinge are not blocked. Do not use your Mac on soft surfaces like beds or pillows — they block bottom vents on laptops
- If you use your Mac for sustained heavy work (video editing, compiling, etc.), consider a laptop stand that elevates the bottom for better airflow, or a cooling pad with fans
- Check for macOS updates — System Settings > General > Software Update. Thermal management improvements ship in updates regularly, especially for newer hardware
- macOS does not show exact CPU temperatures in a built-in app. If you need to see actual numbers, third-party monitoring utilities can read the temperature sensors on both Intel and Apple Silicon Macs
- If your Mac is several years old and consistently hotter than it used to be, the thermal paste between the CPU and heat sink may have dried out. This is a repair shop job — they remove the old paste and apply fresh compound
Frequently Asked Questions
What CPU temperature is too high?▾
It depends on the processor, but as a general rule: below 80 degrees C under load is fine, 80-95 degrees C is warm but usually within spec for laptops, and above 95-100 degrees C is where most CPUs start thermal throttling. At idle, anything above 60 degrees C suggests something is wrong (a stuck process, blocked vents, or dried thermal paste).
Is thermal throttling bad for my computer?▾
Thermal throttling is a safety feature, not damage. When the CPU gets too hot, it slows itself down to generate less heat. Your computer will feel slower while throttling, but the hardware is being protected. The problem is whatever is causing the excessive heat in the first place, not the throttling itself.
How often should I clean the dust out of my computer?▾
For most environments, once or twice a year is enough. If you have pets, live in a dusty area, or keep your desktop on the floor, clean every three to four months. Laptops accumulate dust faster than desktops because of their smaller vents and tighter internal spacing.
Can a laptop cooling pad really help?▾
Yes, but the effect varies. A good cooling pad with active fans can lower temperatures by 5-10 degrees C, which can be the difference between throttling and not throttling. A passive stand that just elevates the laptop helps too, but less dramatically. Either way, the improvement comes from getting more air under the laptop and away from the vents.
Should I repaste my CPU?▾
If your computer is more than 3-4 years old and runs significantly hotter than it used to despite cleaning the fans and vents, replacing the thermal paste is worth doing. The paste between the CPU and heat sink dries out over time and loses its ability to transfer heat efficiently. Desktop CPUs are easy to repaste yourself. Laptops usually require disassembly — consider a repair shop if you are not comfortable with that.