Recommended for all macOS Tahoe users who have a slower Mac: Mac fans can spin up due to CPU and GPU resources

[ghost]

Upon further testing in macOS Tahoe, the fans can spin up when using the OS (even when your fans are cleaned and the thermal paste has been changed). My Mac's fans did 7 times within the last 11 hours. To remedy this, I highly recommend installing a fan control app such as Macs fans control to keep the fans at normal levels and to keep your Mac running cool. Download here: https://crystalidea.com/macs-fan-control/download

Also, enable Reduce Transparency (Optional) to reduce GPU processes (System Settings > Accessibility > Display > Reduce Transparency)

[albert-mueller]

I also highly recommend to clean the fans and put a new thermal paste as the old one for the iMac 2017 is very very outdated. 2017 was 9 yrs ago! You definitely don’t want to operate a computer with a 9 year old thermal paste!

[ghost]

My Mac was refurbished. But still very good idea.