Nice one Krusty!
You are right of course and I could have posted more clearly.
What I should have said is I chuck out the noisy fan and put a nice quiet one back in it's place. preferably an even more efficient one.
In my current PC case I fitted heat sensors as well as adjustable speed fans and have monitored the temperatures (in various hot spots) which is I agree, critical to your computers well being. There was a time when a CPU only needed a passive heat sink. We could well be heading in that direction again, although I cannot see the day when a complete system will be cooled by fanless convection and conduction!
My concerns about fans on Grapic cards probably amounts to the fact that I do not know how easy it is to replace them! Every other fan in the case including the ones in the PSU, I know how to manage.
Its all pretty simple physics, If you know the heat loads in the case then you know what air you need to shift through the case to cool it based on the temperature difference between intake and exhaust. In addition to moving the right volume of air through the case you also try to ensure the heat is being taken away from the right places inside the case to keep the hot spots as cool as possible hence the little fans on CPU's and GPU's(when fitted

). But remember its not the fans that do the cooling its the heat exchanger and the air you move over it. Fans simply focus the movement of the air over the exchanger and move it more quickly. A good heat exchanger may not need the assistance of a fan.
When it come to water cooling the same principle applies.
Rest assurred that there will still be fans in my case, but by careful design and consideration I expect to do the job efficiently with as few as possible.
If you don't have a clue then just bung in fans all over the place and you will probably hit the right bits sometimes!
A bit like aiming on Aces High - some can shoot down with less bullets used than others if they know what they are doing! - I regret I still suck at shooting! but at least my case and components will be cool

Now if you not a Bish and see a spit dweeb hitting nothing you will probably know its me!
Cheers
Blagard