Why is my Mac fan so loud?

It’s not uncommon for a Mac to sound like a jet getting ready for take-off – especially during the warm summer months. Older, Intel-based MacBooks are particularly prone to very noticeable fan noise. So why is your Mac fan so loud? And what can you do about it?

Why are Mac fans so noisy?

In the vast majority of cases, the fans on your Mac are noticeably loud because they’re having to work hard to keep the internal components cool. The alternative would be a lot worse – burnt out components.

In general, you’ll find the fans will kick in when:

• The Mac is doing something demanding, such as video-editing or gaming
• The ambient temperature is warm
• The MacBook is being used on a lap or another soft surface (never put your Mac on a duvet!)
• The Mac has been running for a long period of time

It’s also possible that the fans are making a loud noise because the fan is dirty or faulty, or because of some other fault with the computer. Here are a few things you can do to determine if you’ve got faulty or dirty fans.

How do I tell if I’ve got a faulty Mac fan?

I’ve mentioned it before, but the brilliant iStat Menus is great for identifying problems with your Mac. This powerful utility not only provides a barrage of temperature readings from inside your Mac, but reveals the fan speeds too. So, for example, if your fans are running at relatively slow speeds (less than 2,000 rpm) but making a loud noise, it might be that the fans are dirty/faulty.

If iStat Menus shows the fans are noisy because they’re running at full pelt, it can also help you identify what might be causing that. For example, the app provides a graphical breakdown of what processes are putting the strain on your CPU. If an app is constantly thrashing your processor, that’s going to heat the system and likely cause the fans to kick-in.

iStat Menus also shows the current temperature readings from airflows, the laptop battery, all the core components and even the palm rests. If one of these is unusually high, it might indicate that an airflow is being blocked, forcing the fans to counteract the heat, or that a component is failing. If it’s the latter, you will probably need to seek professional help.

How do I clean my Mac fans?

To be brutally honest, this is not a job I’d recommend for 90% of Mac owners. Devices such as MacBooks and iMacs are not easy to get into without specialist tools, and even if you can get access, locating and cleaning the fans isn’t easy. Get it wrong and you could easily bork your Mac.

I’d recommend leaving such jobs to professional repairers, who will have the right tools and be able to advise you if the fans need cleaning or replacing.

If you have an older Mac Pro that does allow easy access to the internals, Lee’s guide to cleaning noisy fans might well do the trick.

Can I use software to control loud Mac fans?

There are software packages available, such as smcFanControl, that allow you to take manual control of the speed of your Mac fans. However, I strongly recommend you do not use these to control fan noise, unless you’re 100% sure of what you’re doing.

The Mac will automatically determine the speed of the fans based on the cooling required to stop components overheating. If you manually interfere with fan speeds, you could easily prompt components to overheat. At best, that will make your Mac unstable, with the Mac suddenly shutting itself down to prevent component damage. At worst, you could burn out components. Any warranty would also likely be invalidated.

Is there anything else I can try?

If you’ve got an Intel-based Mac and it’s running the fans at full pelt from when you first switch the Mac on, you might try resetting the system management controller (SMC). These can occasionally go haywire, prompting the fans to kick in when not necessary. To reset the SMC, follow Apple’s instructions here.

MacBook owners could also try putting their laptop on a stand. This increases the surface area available for cooling and might prevent those noisy fans from starting so readily.

You’ll also find Amazon is stuffed with expensive cooling mats for laptops, many of which have built-in fans themselves! Personally, I’d avoid these…