I have an AMD Athlon 2500+ fsb333mhz. I have a Dragon case which has 4 fan spots. At first i had only 1 fan in there and i thought it was fine. Then when i moved my machine to a different spot in my room.. it went up in temp around 10* (I moved it away from the window that apparently leaked cold air in gotta love dorms) so i added 3 more fans and it went back to about the normal temp. The thing is now my machine is a bit louder. So i say it depends on if you care if your machine is loud or not. If you dont mind it getting louder... i say add as many fans as possible and if you do so, go for fans around 21db... they are rather quiet compared to the rest. I hope all that helped!