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After changing power supply my fan is running full speed? Why

Hi The reason why your iMac is going max on the fans could be due to a couple things A temperature sensor may have been knocked causing it to go too fast Or there might have been a temperature sensor on the power supply it self But not all hope is lost because you can do the hard thing :open it up again and fix the issue once we have diagnosed it Or we can do the easy method Which is download and install Mac fan control Mac fan controls is a neat little pice of software that allows you to control your macs fans Here’s a link for the download! https://crystalidea.com/macs-fan-control Hopefully this answers your question Thanks:-)