Thanks for the info, tbh you just validated my decision not to buy it. My 2015 iMac 5k has become really loud since the Catalina update when running an external display, even after replacing the fan and power unit. The fan noise is biggest reason I'm looking for an upgrade. It's a shame really because it is running otherwise flawlessly. I don't even mind a little noise, but when I can hear it with noise cancelling headphones it's problem!