[X4U] PowerBook in "lid closed" mode

[James S Jones]

At least in the aluminum PowerBooks, the keyboard is not a part of the 
cooling system. It it were, the keys would be noticeably warm to the 
touch--and they're not. Air enters from the vents on the bottom front 
and exhausts from the vents in the back, where the hinge pivots. I 
believe the titanium models worked in much the same way, but I have 
very little experience with them. The pivot of the lid doesn't restrict 
airflow from the exhaust vent in any position, so it should run at more 
or less the same temperature, open or closed.

I would suggest running a utility such as Temperature Monitor and then 
experimenting with the lid both open and closed. Since the temp will 
show in the menu bar (or, Dock), it will be easy to tell if heat 
buildup reaches a critical level.

BTW, regardless of the lid position, I would recommend one of the 
several products that lift the PB above the work surface. Most of the 
heat accumulates on the bottom of the case, below the CPU, GPU, 
battery, and drives. Increasing airflow over the underside makes a 
clear difference in my experience. To quote from the Apple PB care 
page: "The bottom of the PowerBook case functions as a cooling surface 
that transfers heat from inside the computer to the cooler air outside. 
The bottom of the case is raised slightly to allow airflow that keeps 
the unit within normal operating temperatures. In addition, the 
computer vents warm air from the back of the case."

On Feb 20, 2005, at 3:45 PM, Jeff Winchester wrote:

> My understanding is that the keyboard assembly of the G4 PowerBook 
> acts like a heat sink, drawing heat away from the inside of the 
> machine. Assuming this is correct, to close the lid would deprive the 
> system of this ability.
>
> Is it safe for constant use in this mode?