2019 iMac desktop is making a loud fan noise.

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Level 1

10 points

2019 iMac desktop is making a loud fan noise.

Hello, I have a 2019 Retina 5K 27-inch iMac desktop that's making a loud fan noise. Not always, but often enough that I'm concerned that it's a problem that needs to be fixed before it dies on me.

I can't remember exactly when this started, but it was approximately around the same time that I upgraded from Mojave to Big Sur. I have no idea if that would have any impact, but I've had a couple of other minor problems since I upgraded so I thought I'd mention it.

If anyone has had a similar experience with the fan issue, I'd love to hear from you.

Thank you,

Robbi

MacBook Pro 15″, 10.15

Posted on Sep 3, 2021 6:36 PM

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Answer 1

Top-ranking reply

den.thed

Level 10

82,540 points

Sep 3, 2021 7:06 PM in response to robbi5318

Go to Applications > Utilities and open Activity Monitor.

https://support.apple.com/guide/activity-monitor/welcome/mac

Then look for a high CPU, unresponsive or failed process when the fan is acting up.

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Answer 2

Allan Jones

Level 9

72,368 points

Sep 3, 2021 7:10 PM in response to robbi5318

The fan in all Macs is thermostatically controlled. At idle, they run slow enough that you to need a very quiet room to hear it. As temps rise, the fans speed up to protect components from thermal damage. The fans are quite audible when running at full speed (about 2700rpm in my iMac 2017 5K 27")

About fans and fan noise in your Apple product - Apple Support

Heat will build up and speeds increase under a number of conditions, including:

Watching videos
Doing video conferencing
Gaming

In addition, running anti-virus apps or so-called "cleaning apps" will create higher temps.

There are vents on the iMac that you MUST respect or see higher temps. Intake vents are on the bottom of the display unit:

DO NOT place anything between the desk and the vents. The iMac needs all of the ~3 inches/75mm of clearance for effective cooling.

The exhaust vent is inconveniently close to the stand the support the iMac:

Tipping the display fully forward WILL partially block the exhaust vent and run up the temps significantly. I can create the issue at will on my iMac.

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Answer 3

robbi5318 Author

Level 1

10 points

Sep 3, 2021 8:32 PM in response to Allan Jones

Thank you for taking the time to gather so much information for me! On your list of possible causes for this problem, I'm guilty of all of them. I keep a notebook under my iMac leaving me with only 2" clearance on the right side. My office is much hotter in the summer months, and I'm also taking a class that requires me to watch a lot of video's It also just hit me that the fan often runs at high speeds when I'm working on a project in Photoshop and have other photo programs running at the same time.

I'll make those adjustments and see what happens.

Thanks again :)

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Answer 4

robbi5318 Author

Level 1

10 points

Sep 3, 2021 8:47 PM in response to den.thed

Thank you for getting back to me so quickly. The article on the link you sent me has a lot of valuable information. I have very little experience using the Utilities and Activity Monitor Application so I appreciate the thorough explanation.

This is the first time I've checked out Community Support on this website. There are a lot of smart people on here!

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2019 iMac desktop is making a loud fan noise.

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