Closed Powerbook Causing Heat Damage


If one were to run a program/hack that allowed the powerbook to function completely (aka not sleep mode with full processing, internet connection, etc) without an external monitor hookup, could this cause heat issues which could damage the notebook? Is there any documentation of such online as I have heard from people who work on them that it can, and Apple would make it an option if it didn't, but am looking for an answer either way.
Why would it? The only difference between a PowerBook being used in closed-lid mode with a monitor attached and a PowerBook being used in closed-lid mode with no monitor attached is one cable connected to the back of the PowerBook.

One cable is not going to significantly impact heat dissipation by the PowerBook.

It's perfectly safe to run the PowerBook like this. To ease your mind, here's a tech document directly from Apple explaining how to do this:

I don't even think you need a hack to do this... to do this without a monitor attached, I would assume that you just hook up an external USB keyboard/mouse, close the lid of the PowerBook, then press a key to bring it back to life. Then disconnect keyboard/mouse.

Who, exactly, are these "people that work on them?" If they told you that operating the PowerBook in closed-lid mode can damage it, then they're giving out inaccurate information.