The fan inside your Mac serves an important purpose – it helps keep the internal components cool. However, excessive fan noise can be distracting and annoying. You may want to control your Mac’s fan for a few reasons:
The fan is constantly running at high speed even when you’re not doing processor-intensive tasks. This creates distracting ambient noise, especially if you’re in a quiet environment.
The fans ramp up intermittently, creating a sudden increase in fan noise. These bursts of fan noise can interrupt concentration.
Your Mac is getting older and the fans seem to be working harder to keep it cool, resulting in loud fan noise.
Controlling your Mac’s fan can help reduce ambient noise and distractions, allow you to better concentrate, and potentially extend the lifespan of your Mac by reducing wear on the fans.
Check Your Mac’s Fan Settings
The first step is to check your Mac’s existing fan settings. You can adjust the fan behavior in System Preferences > Energy Saver.
To get there, click the Apple menu in the top left and select System Preferences. Then click Energy Saver, which has an icon that looks like a light bulb.
In the Energy Saver settings, you’ll see options for “Turn display off after” and “Put hard disks to sleep when possible.” Adjusting these to shorter time periods can help reduce fan usage. You can also check the “Prevent computer from sleeping automatically when the display is off” box. This keeps the computer active even with the display off, which may impact fan activity.
After adjusting settings in Energy Saver, you can monitor any changes in fan behavior. Note that the fan settings here are fairly basic, so you may need other solutions to fully control or reduce fan speed.
Adjust the System Preferences
One way to reduce fan usage on your Mac is to adjust the System Preferences. Under System Preferences > Energy Saver, you can limit the maximum processor performance. This prevents your Mac’s CPU from turbo boosting to higher speeds which often increases heat and fan activity.
To limit processor performance:
- Go to System Preferences > Energy Saver.
- Click the “Battery” tab.
- Drag the “Processor Performance” slider to the left to limit maximum performance. Try reducing it in increments and testing to find an optimal balance of performance vs fan noise.
You can also try changing the option “Automatic graphics switching” to limit GPU usage. Reducing components like CPU and GPU performance will reduce heat output and therefore allow fans to spin slower.
Keep in mind limiting processor performance can reduce computer speed for intensive tasks. Find a balance which works for your usage needs.
Use an App to Control the Fan
One option to control your Mac’s fan speed is to use a third-party app like Macs Fan Control. This free and open-source app gives you granular control over your fan speeds and can help optimize cooling and reduce fan noise.
With Macs Fan Control, you can manually set custom fan speeds for different temperature ranges. There is also an automatic mode that will adjust the fans based on the current CPU temperature. You can control both the CPU and chassis fans independently.
Other key features of Macs Fan Control include:
- Setup custom fan speed profiles for different usages like gaming or video editing
- Control the number of fan sensors used
- Minimize fan speeds and noise during less intensive tasks
- Displays current fan speeds and temps in the menu bar
So if you want more granular control over your Mac’s fans, an app like Macs Fan Control provides advanced options not available through System Preferences alone. With the ability to customize fan speeds, you can optimize cooling and noise based on your usage.
Check for Dust Buildup
Dust buildup inside your MacBook can prevent proper heat dissipation by clogging the fan and airflow vents. Over time, dust, pet hair, and other particles can accumulate inside your laptop. As air intake becomes restricted, the fan spins faster in an attempt to cool the system, which leads to loud fan noise. Excessive heat also puts strain on components like the CPU and GPU, potentially shortening their lifespan. It’s a good idea to periodically clean the inside of your MacBook to remove this buildup.
To check for dust, first power off and unplug your MacBook. Then use a Phillips head screwdriver to remove the bottom case. Refer to this iFixit guide for step-by-step instructions. With the bottom case removed, you’ll have access to the fan and heatsink. Use a flashlight to look for dust accumulation. Pay special attention to the fan blades, vents, and heat fins. If a significant amount of dust is present, you should thoroughly clean out the inside of your MacBook.
Use a can of compressed air to blast away most of the loose dust. Hold the can upright and spray short bursts as you move the nozzle around. After most of the dust is gone, you can use a cotton swab dampened with isopropyl alcohol to gently clean more stubborn dust stuck on surfaces. Be very careful not to get any liquid on electronic components. Allow your MacBook to fully dry before reassembling.
Reset the SMC
The System Management Controller (SMC) oversees your Mac’s fans and temperature sensors. Resetting the SMC can help clear any issues that are preventing your fans from properly turning on or off. To reset the SMC on an Intel-based Mac:
- Shut down your Mac
- Unplug the power cable and wait 15 seconds
- Plug the power cable back in and wait for your Mac to turn on
- After your Mac turns on, release the power button
This reset process clears the SMC and allows it to restart fresh, which can resolve fan issues caused by faulty management. Resetting SMC resets your computer’s fan speed management and clears any stuck settings that could be preventing your fans from properly turning on or off (1). After resetting SMC, your Mac’s fans should once again automatically adjust their speeds based on system needs.
(1) https://www.avast.com/c-reset-mac-pram-smc
Test in Safe Mode
One way to check if a software issue is causing the fans to run constantly is to boot your Mac into Safe Mode. Safe Mode loads only essential macOS files and features needed for basic functionality. This eliminates any login items, fonts, kernel extensions, and other software that could be interfering with the fans.
To enter Safe Mode, first shut down your Mac. Then turn it back on and immediately press and hold the Shift key. Keep holding Shift until you see the login window with “Safe Mode” in the upper right corner. Now login normally and use the Mac to see if the fans still run constantly. If the fans operate normally in Safe Mode, that points to a software issue rather than hardware.
Safe Mode can help isolate software culprits. Check for any recent system changes, updates, new apps, or configurations that could be problematic. If reverting back to an earlier setup solves the fan issue, you’ve found the cause.
Replace Thermal Paste
Replacing the thermal paste between the CPU/GPU and the heat sink can significantly improve heat transfer and lower your Mac’s internal temperatures. Thermal paste dries out and becomes less effective over time. Reapplying high quality thermal paste like Arctic MX-4 can reduce your CPU temperature by 10°C or more.
To replace the thermal paste, you will need to open up your iMac and detach the heat sink from the logic board to expose the CPU and GPU chips. Clean off the old thermal paste from the chips and heat sink using isopropyl alcohol and a lint-free cloth. Then apply a small line or dots of fresh thermal paste before reattaching the heat sink. Refer to iFixit’s thermal paste replacement guide for detailed steps.
Replacing the thermal paste requires disassembling the iMac, so it’s recommended to be comfortable working inside computers. If you’d rather not open up your iMac, consider taking it to an Apple store or authorized service provider for a professional thermal paste replacement.
Consider an External Fan
Using an external fan or cooling pad is an easy way to improve airflow and lower temperatures for your Mac. External fans sit underneath the Mac and blow cool air into the vents, creating more airflow inside the chassis. This extra cooling effect can lower the internal temperature by up to 20°F or more (1).
There are many affordable and effective options to choose from, like the Havit Laptop Cooling Pad which has three adjustable height settings to direct airflow as needed. Cooling pads with larger fans that align well with the Mac’s air vents tend to provide the best performance. Models with built-in USB ports are convenient for powering the fan while still using the other ports on your Mac.
While integrated fans and heat sinks do the bulk of the work, getting that extra cooling boost from an external fan can make a meaningful difference during intensive tasks or hot conditions. Just make sure the fans are lined up properly with the vents on the bottom of your Mac. With lower chassis temperatures, the internal fans don’t have to work as hard either.
(1) https://macpaw.com/reviews/best-macbook-cooling-pads
When to Take it to the Apple Store
While many common fan issues can be resolved on your own with simple cleaning or software changes, sometimes a constantly spinning fan is indicative of a larger problem. If you’ve tried the troubleshooting steps above and your Mac’s fan is still constantly running at full speed, it’s a good idea to take it into an Apple Store or Apple Authorized Service Provider for evaluation.
Some potential underlying issues that could be causing fan problems include:1
- Faulty temperature sensors
- Failing logic board components
- Thermal paste needs to be reapplied
- Damaged fan cables or connectors
Apple technicians have the necessary tools and expertise to run diagnostics and determine if your fan issue is a symptom of a larger hardware problem. They can then advise you on the best repair options, which could range from a simple fan replacement to a more involved logic board repair.
It’s generally a good idea to have Apple evaluate a constantly running loud fan before the end of your warranty or AppleCare coverage period. Fan issues can sometimes lead to overheating and damage other components if left unchecked. Getting an expert assessment quickly when software fixes don’t work can help prevent further issues down the line.