Chosen Solution
As soon as I turn my imac on the fan starts screaming. it was never quiet but has become increasingly unbearable.Would a new fan help?
Your imac might be overheating that may be why the fans are louder. Higher temperature readings will speed up the fans. Remove all dust from vents and heat sink especially under the heat sink cover I always use a shop vac to vacuum the dust just be careful with the fans. reapply thermal paste, use the good stuff like Arctic Silver 5 or Arctic Silver Ceramique. The Ceramique stuff is cheaper and is non conductive so it is safer. Also lubricate the fans with a non conductive lubricant, I like to use sewing machine oil. The fans will spin faster and quieter once they are cleaned and lubricated decreasing noise and temperatures. I would advise you to do this sometime in the near future because the higher temperatures will more than likely cause the GPU to malfunction.
Have you upgraded or added anything to the computer recently? I would check the fans as suggested but also if any of the thermal sensors are not seated correctly that will cause the fans to run constantly.
Thanks for all the input. I haven’t done anything to it recently. I’ll try this stuff and hope it helps.
