if your noisy machine is a laptop, it’s quite likely that the heat exchanger is plugged w/ lint/dust. very easy to fix. typically a screwdriver, small brush, vacuum cleaner. don’t blow the dust...you’ll only push it into places you can’t reach. youtube &/or manufacturer’s site will show you how to do it. if yours is a desktop, could easily be similar situation for CPU heat-sink/fan &/or powersupply fan. all easy to fix. dust is not your friend, it prevents cooling. hot processor throttles itself down in speed = slower computer.
Thanks for the suggestions - I’ll try them. It was pretty noisy from day one, though.