I keep reading of 'wizzing fans' *This may seem trivial but it isn't*. Look at the fans, make sure they are spotlessly clean
I can't speak for others but mine are spotless; every few months the fans get a clean and the inlet and exhaust grilles cleared of fluff, the last time being a week ago. The "wheeee" I referred to in my post is the high speed running of the fans before boot commences. When it does, the fans appear to slow down and become a near silent "whoooo".