For those of you wondering why your PowerBook (DVI) is so noisy:
The “purring” noise us caused by resonation when the ATI graphics chipset in the PowerBook (DVI) refreshes a large area of the screen, such as when a web browser scrolls and/or renders a page. The PowerBook (DVI) has no shiedling below the keyboard, to improve heat dissipation, at the expense of a little more noise. Most previous models (like the previous generation PowerBook G3 and the iBook Dual USB) have such shielding.
Other sounds to note: If the OEM 40 meg hard drive does a “long read” (a read of a single file scattered across the hard drive, or a search of the catalog b-tree) you’ll hear a high-pitched sound. It’s not harmful, so just ignore it. While on battery, you may hear the speakers “pop” or “hiss” before a sound plays, as well as a delay in program responsiveness – this is because OS X powers down the sound chipset when it’s not being used for a while, and it must be switched back on and initialized before sound can play.
And to round up the common noise descriptions, if you hear a faint, steady whistling from your PowerBook (DVI), it’s the fan running at a very, very low speed – it’s able to run at a lower speed than the previous model. And last, the AC adapter buzzes slightly.
Does that cover it all?
