My Mac Starts Making a Loud Whirring Noise After Being On for Two Minutesby Nicole Vulcan ; Updated September 28, 2017
If you're experiencing a loud whirring noise soon after you turn on your Mac computer, you're likely hearing the computer's internal fans kick in. The fans are there to help keep your computer cool -- and often turn on when you're doing tasks that are especially intensive. But if your fans are turning on soon after your computer is turned on, chances are you haven't had time to get too deeply involved in intensive work. In that case, a number of things may be causing your fans to turn on.
If air cannot escape your machine, it could be getting extra hot in there, causing your fans to kick in right after bootup. Check the vents of the computer as well as any other holes in the computer's body. If they're clogged with dust, use a vacuum to remove the dust -- and repeat the process often to avoid dust build-up in the future.
Finding an Errant Process
Sometimes an errant program may be running in the background, causing your CPU to work overtime and your fans to turn on. To check whether any programs are taking up excess CPU, you can use a handy tool installed on your Mac. In the Finder, enter "Activity Monitor" without quotes, press "Enter" and then click on the Activity Monitor icon to open it. Then check the percentage of CPU that each individual program is using. To make it stop, you may have to perform a force quit. Click on that program's title in the list and then click "Quit Process" from the top of the Activity Monitor. Then confirm that you want to perform either a "Force Quit" or simply "Quit" the program in the popup window.
Another way to stop the annoying fan noise is to have more control over when the fans turn on. You can do this by downloading a fan control software designed for Mac. Choices include smcFanControl from eidac, Fan Control 1.2 from Lobotomo Software and MacBook/Pro Extended Fan Control from Derman Enterprises. The programs allow you to change the temperature at which your fans kick in, although most programs will not go below Apple's recommended settings.
All Macs also come with a piece of software that allows you to determine whether the problem you are having is a result of a piece of your computer's hardware. The Apple Hardware Test can be a handy tool if you still can't get your fans to operate correctly. To run it, turn off your computer and then turn it back on. When you see the grey startup screen, hold down the "D" key. You'll then be able to choose which hardware tests to perform at the next screen.