Mac Fan Control

Your Mac controls its fans automatically. macOS speeds them up as temperatures climb and slows them down, or stops them, as the Mac cools. For everyday use you don't need to change anything. A fan control app helps when you want to choose the balance yourself, for example to keep a Mac cooler through a long render or export.

How Mac fans work

Every Mac with a fan has a controller, the System Management Controller (SMC), that reads the temperature sensors and sets fan speed. Each fan has its own minimum and maximum speed, measured in RPM (revolutions per minute).

Under light work, the fans on many Apple silicon Macs stay at their minimum or stop entirely. When the chip runs hot for longer, they ramp up. If that isn't enough, macOS lowers the chip's speed to keep temperatures safe. That's thermal throttling, and it's a protection, not a fault.

Apple silicon and Intel

Apple silicon Macs produce much less heat for the same work, so their fans run less often and more quietly. Many people rarely hear them. Intel Macs run hotter, reach high fan speeds sooner and throttle more under sustained load. Manual control usually makes a bigger difference on Intel Macs.

MacBook Air has no fan

Every MacBook Air with Apple silicon, from M1 onward, is cooled without a fan, so there's nothing to control. Under sustained load it slows down to stay within safe temperatures instead. You can still watch its temperatures with a temperature monitor. Intel MacBook Air models do have a fan.

When manual fan control makes sense

• Long, heavy jobs. Video exports, 3D renders, large code builds and games can run for an hour or more. Raising fan speed earlier keeps the chip cooler and can reduce throttling.
• Getting ahead of the heat. Starting the fans before a big job, instead of waiting for macOS to react, keeps temperatures lower from the start.
• A cooler case. On a MacBook Pro, higher fan speed keeps the keyboard and bottom case cooler to the touch.
• Your own balance. A custom curve lets you decide how loud the Mac gets at each temperature.

When it doesn't help

• A hardware problem. If a fan rattles, grinds or never spins, contact Apple. Software can't fix a failing fan.
• A hot Mac that should be idle. If the Mac is hot while you do very little, something is running in the background. Find it with a task manager, or read MacBook overheating.
• Full speed all day. It adds noise and fan wear for little gain when the Mac isn't working hard.
• Going below the minimum. A fan slower than its minimum can't cool the Mac properly. SystemWatch never sets a fan below its minimum.

How SystemWatch controls fans

Fan control is part of SystemWatch's website edition. App Store rules don't allow apps to read temperatures or change fan speeds, so the App Store edition doesn't include it.

• A small helper. Changing fan speeds needs administrator rights, so SystemWatch installs a helper. You allow it once in System Settings › General › Login Items & Extensions. The helper does one job, reading and setting fan speeds, and it only accepts requests from SystemWatch itself, checked by its code signature.
• Speeds stay in each fan's range. The helper only sets speeds between each fan's own minimum and maximum, as reported by the Mac. After each change it reads the speed back. If a fan won't hold a safe speed, it goes back to automatic.
• Custom curves. Pick the temperature to follow, such as the processor's hottest core or any single sensor. Then drag points to set the fan speed for each temperature, where 0% is the fan's slowest speed and 100% its fastest. Quiet, Balanced and Cool presets give you a starting point.
• Fixed speed or full speed. Hold one speed, or send every fan to full speed in one click.
• macOS takes over again. When you quit SystemWatch, the fans go back to automatic. If the app stops responding, the helper notices within about 15 seconds and does the same. If the processor reaches 95 °C while a fan is set below its maximum, that fan goes back to macOS until the processor cools to 85 °C, and then your setting returns.
• Back to Automatic. One button returns every fan to macOS. You can uninstall the helper from the same screen.

Fan speeds sit next to every temperature sensor in the Sensors view, so you can see what each change does.

Supported Macs

Fan control works on Apple silicon Macs, including M5, and on Intel Macs with fans. SystemWatch needs macOS 15 or later.

The website edition is a one-time $5.99 lifetime license (launch price for the first 100 copies, then $14.99) for up to 3 Macs. Besides fans, it reads every temperature sensor, shows power in watts and core frequencies, and adds quit and force quit, a Startup Items manager and Deep Clean.