> Not to argue, but is this really true? I have 2 points: > > 1) The aluminum 12" (as well as 15" and 17") is made to run with the > lid down in extended desktop mode, and it runs a G4 at higher speeds. > One would think those could get even hotter! The Powerbook models have more effective cooling systems; both because the processors generate higher temperatures (they have slightly faster G4 processors than those used in the iBook), and because the've been specifically /designed/ to function when closed. This is a feature of the professional model -- not a firmware hack. > 2) If you lift your keyboard out, you'll notice that there's no > ventilation on the bottom of the keyboard...it's a flat piece of > plastic/metal. It seems like it would prevent air from flowing thru > the keyboard...so maybe this isn't really a concern? That metal could also be used to conduct heat away from the interior; the processor is not necessarily cooled by air currents from the fan alone. If I'm not mistaken, I think in most cases the fan is there to cool the heat sinks and heat exchangers that do a more efficient job of conducting heat away from the processor; not so much the processor itself. Just because the iBook /can/ be hacked to do this doesn't necessarily mean it's a good idea, and it's almost certainly not something you want to do in the long term. Excessive heat will shorten the life of the components, and can also cause sudden, unexpected failures. (There's a reason why the Power Mac G5 is configured the way it is with several different fans; and why -- if I recall correctly-- it will go into sleep mode automatically if one of them fails. Heat is not your friend.