If you face Fan Noise issue in normal usage also like only using for music or excel or just internet surfing on safari then see what you can do to fix This first step to do is resect SMC after updating to Catalina so that any old data should be removed from the cache.So you replaced the SSD in your imac and now the fan is going 100%? Easy solution, get TG Pro, which is fan control software.Fortunately, weeks ago I had installed a Time Machine backup to a USB hard drive and was able to boot the iMac using this USB hard drive, and then use the Disk Utility to format the SSD that I'd installed then reboot with just the Time Machine disk attached. After installing it, booting the iMac using the SSD got the flashing question mark.Fan management in Apple systems relies on temperatures reported by the SMC system. iMac users who tweak their systems using 3rd party hard disks or solid state disks, are often surprised by an unpleasant aftermath: an annoyingly noisy hard disk fan.
