If your 2-3 year old Mac is running very hot and slows down after a minute of heavy use, clean out the dust from the cooling system instead of buying a new
Why is my iMac so loud? - Hero Tech Support
Clean out that dust in your Apple iMac - SPARK Services
Clean out that dust in your Apple iMac - SPARK Services
How to clean iMac fan without opening - OurDeal.co.uk
❄️🛠️ 🖥️ iMac 27" 2012-2015 System Fan Replacement - YouTube