A Mac that heats up isn't necessarily a fault. All computers produce heat when they work, and Macs are no exception. The processor (CPU) and graphics processor (GPU) naturally generate heat when they're being used. The cooling system, consisting of one or more fans and heat pipes, is designed to remove this heat.
The problem starts when the heat exceeds what the system can remove. The fans then run at full speed to compensate, creating that characteristic wind tunnel noise that is so worrying. In severe cases, the Mac deliberately slows down its performance (this is called the thermal throttling) to avoid damaging the components.
In 15 years of repair work in Brussels, we have found that overheating is one of the five most common reasons for consultation. The good news is that in the vast majority of cases, the problem can be resolved without replacing any parts.
Before moving on to solutions, it's important to understand what causes overheating. Here are the most common causes we diagnose in the workshop:
| Cause | Frequency | Gravity | Solution |
|---|---|---|---|
| Accumulated dust | Very frequent | Average | Internal cleaning |
| Background-intensive applications | Very frequent | Low | Activity monitor |
| Used thermal paste | Frequent (Mac 3 years and over) | Average | Paste replacement |
| Too many browser tabs | Frequent | Low | Close unnecessary tabs |
| macOS or obsolete apps | Moderate | Low | Updates |
| Faulty fan | Rare | High | Fan replacement |
| Surface blocking ventilation | Frequent | Low | Change surface |
| Thermal sensor faulty | Rare | High | Workshop diagnosis |
The first thing to do when faced with an overheating Mac is to identify what's consuming resources. The Activity Monitor is the tool built into macOS that shows you exactly which processes are using up your processor.
Open the Finder, go to Applications, then Utilities, and launch Activity Monitor. You can also find it quickly with Spotlight: press Cmd + Space and type «Activity Monitor».
Once open, click on the CPU at the top of the window and sort by % CPU by clicking on the column header. The most power-hungry processes appear at the top.
| CPU usage | Situation | Action |
|---|---|---|
| 0 to 30 % | Normal, light use | No action required |
| 30 to 70 % | Moderate load, fans possible | Monitoring dominant processes |
| 70 to 100 % | High load, fans likely | Identify and close unnecessary processes |
| A continuous 100 % process | Blocked process or malware | Force exit or launch an antivirus scan |
If a process you don't recognise is consuming more than 80 % of CPU continuously, it may be malware. In this case, consult our Mac antivirus security guide to scan.
Some applications are notorious for making heavy demands on the processor, especially on older Macs. The usual culprits are video editing software (Final Cut Pro, Premiere Pro), photo editing software (Photoshop, Lightroom), video conferencing applications (Zoom, Teams, Google Meet) and certain games.
To force the closure of an application that is blocked or too greedy:
Press the Cmd + Option + Escape to open the «Force Quit» window. Select the problematic application and click on «Force Quit». You can also right-click on the application icon in the Dock and choose «Force Quit».
If your Mac is generally slow and heats up even with few applications open, the problem may lie deeper. Our guide to solving a slow Mac details 12 additional optimisation solutions.
This is a cause of overheating that many people underestimate. Each tab opened in Chrome, Safari or Firefox consumes memory and CPU, especially if the pages contain videos, animations or interactive ads. Having 30 tabs open simultaneously can easily consume 40 to 60 % of CPU resources.
Chrome is particularly greedy because each tab runs as a separate process. Safari, which is optimised for macOS, manages resources better but is not immune to large numbers of tabs.
A few simple habits will considerably reduce the heat load: close tabs that you are not actively viewing, use extensions such as «The Great Suspender» (Chrome) or «Tab Suspender» (Firefox) that put inactive tabs to sleep, and avoid running videos in the background.
Updates to macOS don't just add new features. They also fix bugs that can cause excessive CPU usage. A poorly optimised system process in an earlier version can loop and generate heat unnecessarily.
To check for updates, open System settings (or System Preferences on older versions), then click on General and Software updates. Install any available updates.
Also remember to update applications via the App Store (Updates tab) and directly in third-party applications. An out-of-date version of Spotify, Slack or Discord may contain a bug causing abnormal CPU consumption.
The SMC (System Management Controller) is the chip that manages your Mac's fans, battery, lights and thermal management. When the SMC malfunctions, the fans may spin at full speed for no apparent reason, or fail to kick in when they should.
Switch off your MacBook. Hold down the Ctrl + Option + Shift (left side) for 7 seconds, then add the power button and hold the four buttons together for a further 7 seconds. Release everything, wait a few seconds, then switch on again as normal.
Switch off your MacBook. Hold Shift + Ctrl + Option (left side) and the power button for 10 seconds. Release everything, then switch it back on.
Turn off the Mac, unplug the power cable, wait 15 seconds, plug it back in and wait 5 seconds before turning it back on.
For a complete guide to resetting your Mac, see our Mac reset tutorial.
The air vents on your Mac are where the hot air exits. On a MacBook, they are located along the hinge, between the screen and the keyboard. On an iMac, they're located under the screen and at the back. On a Mac mini, they are at the bottom of the case.
Over time, dust, pet hair and fibres accumulate on these grilles and reduce airflow. Sometimes an external cleaning is all it takes to see a noticeable improvement:
Switch off your Mac and unplug it. Use a compressed air canister (available from electronics shops), keeping the nozzle 10-15 cm from the grilles. Blow in short bursts while tilting the Mac to help the dust out. Avoid tilting the compressed air can, as the liquid propellant could damage the components.
The environment in which you use your Mac plays a major role in its temperature. A MacBook placed on a bed, sofa or lap will have its air vents partially or totally blocked by the fabric.
Here are some best practices:
| Practice | Thermal impact |
|---|---|
| Use a raised stand | Reduces the temperature by 5 to 10°C by improving air circulation under the MacBook |
| Working on a flat, hard surface | Allows vents to function normally |
| Avoid direct sunlight | Aluminium casing absorbs heat quickly |
| Cooling pad with integrated fans | Modest reduction of 3 to 5°C, useful for older Macs |
| Remove the protective cover or shell during intensive use | Shells insulate the case and retain heat |
Thermal paste is the conductive material applied between the processor and the heat sink. Its role is to fill in surface micro-imperfections to optimise heat transfer. Over time - generally after 3 to 5 years - this paste dries, hardens and loses its effectiveness.
Replacing the thermal paste is one of the most effective ways of combating chronic overheating. On Intel Macs from 2015 to 2020 that we treat in our workshops, the benefits are often spectacular: a reduction of 10 to 20°C in the temperature of the processor and fans that become silent again in normal use.
This operation involves dismantling the Mac, removing the heatsink, cleaning the old paste with isopropyl alcohol and applying a quality paste (Arctic MX-6, Thermal Grizzly Kryonaut or equivalent). This is a delicate operation that requires experience: too much paste or uneven application can aggravate the problem.
At Réparation MAC, thermal paste replacement is included in our service. preventive maintenance service, with full cleaning and thermal diagnosis.
When the compressed-air canister no longer suffices, it's because dust has accumulated inside: on the fan blades, around the heat sink, in the nooks and crannies of the case. A MacBook used for 2-3 years in an environment with pets or a lot of dust can have its airflow reduced by 50 % or more.
Internal cleaning involves partially dismantling the Mac: removing the bottom cover on a MacBook, meticulously cleaning the fans and heatsinks with professional compressed air, an antistatic brush and isopropyl alcohol. This is also an opportunity to check the condition of the fan itself (bearings, cable, connector) and the thermal paste.
A lukewarm Mac during intensive use is perfectly normal. But there are certain signs that should alert you and warrant a professional diagnosis:
| Symptom | Probable cause | Emergency |
|---|---|---|
| Fans at full speed all the time, even when at rest | Thermal sensor faulty or SMC blocked | Average |
| Sudden switch-off without warning | Critical overheating, thermal safety activated | High |
| Smell of burning or hot plastic | Damaged component, potential short-circuit | Urgent |
| Keyboard keys are hot to the touch | Dried thermal paste or fan out of order | High |
| No fan noise despite the heat | Fan faulty or cable disconnected | High |
| Severe slowing and jerking | Thermal throttling, the Mac reduces its performance | Average |
If you smell something burning, turn off your Mac immediately and unplug it. Do not turn it back on until you have obtained a professional diagnosis. This type of symptom may indicate a motherboard or battery problem that requires urgent attention.
Yes, a MacBook that feels warm in use is perfectly normal. The processor generates heat and the aluminium casing acts as a heatsink. It's when the Mac becomes hot to the touch or the fans are constantly running that the situation warrants attention.
If your Mac heats up but the fans don't turn on, this could indicate a faulty fan or a problem with the thermal sensor. On Apple Silicon Macs, the fans can remain silent under light load because the chips are very efficient. But if the Mac is burning up without ventilation, get it diagnosed.
macOS does not display the temperature natively. You can use free applications such as Hot (in the menu bar) or Stats (open source). In the workshop, we use professional probes to accurately measure the temperatures of internal components.
Much less than Intel models. Apple Silicon chips are designed to be energy-efficient and produce much less heat. The MacBook Air M1/M2 doesn't even have a fan. Overheating on Apple Silicon is generally caused by poorly optimised software (like some Intel apps running on Rosetta 2).
At Réparation MAC, an internal cleaning with thermal paste replacement is part of our preventive maintenance service. Prices depend on the exact model. You can consult our detailed rates or request a free quote online.
A cooling pad offers a modest reduction of 3 to 5°C, which can help on an older Mac that heats up a lot. However, it's no substitute for internal cleaning or thermal paste replacement. A simple raised stand that improves air circulation under the MacBook is often just as effective and takes up less space.
Macs have thermal protections that shut down the computer before irreversible damage occurs. However, chronic overheating accelerates the ageing of the battery, can degrade the thermal paste more quickly and, in extreme cases, can cause micro-welds to fail on the motherboard.
Yes, the causes are similar: dust, worn thermal paste and greedy software processes. iMacs have the advantage of more internal space for ventilation, but their slim design still collects dust. Cleaning an iMac requires specialist tools because the screen is glued.
Technically, this is possible on MacBooks with accessible Pentalobe screws. However, there are risks: damaging a connector, dislodging a ribbon cable or creating static electricity. If your Mac is still under Apple warranty, opening it by a third party may invalidate it. For a complete cleaning using thermal paste, we recommend a visit to our workshop.
After an update, macOS performs optimisation tasks in the background (Spotlight indexing, APFS compilation) which can last from a few hours to a day. Leave your Mac plugged in and in standby mode overnight. If the overheating persists after 48 hours, check the Activity Monitor to identify an abnormal process.
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