From: "David Gillett"
>  Hard drives and fans generally run at a constant speed, and so their noise 
> tends to be constant too.  This "rev up" sounds like what some machines I've 
> worked with do in order to determine what CD/DVD (or, occasionally, floppy) 
> is in a drive.

"Better fans" have a temperature sensor that runs the speed up and down to
help keep the noise under control.  If a fan is making "that much?" noise, it should
be easy to spot.
                                                              Rick Glazier

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