It was loud, very loud, for the first five to ten minutes my PC made a noise like a jet engine. And then almost silence, as usual. Is the hard disk on the way out, just what I need.
I tried the internet, "Have you tried cleaning the fans? With a vacuum cleaner."
I halted the computer and vacuumed all the holes I could find in the casing. Yep, it was really bunged up with dust. I didn't open the case or unplug anything.
I switched it back on and it was quiet.