So you're saying it's the CPU that makes the high pitched whine?! Errr... In general I agree with your post, but statements like this don't help your credibility an

This quote from a FatBits post should convince you that CPU's can make noise, or trigger noise to be made in other components:

Let's think a bit deeper about this problem. Sure, all computers make some sort of noise. Even without fans there's still the hard drive spinning with its disk heads moving to and fro. Moving parts mean noise. But a power supply? The only things moving in a power supply are electrons, right? AC in, DC out. What's to move?

If you owned one of those 150-in-one kits from RadioShack as a kid (or if you have a degree in electrical engineering...pretty much the same thing, surely) you know full well that analog electronic components can and do move—ever so slightly, mind you—and therefore can make noise. The transformer, in particular, was quite a noise-maker in my 150-in-one kit. Perhaps not surprisingly, one of the many things a transformer can do is convert AC to DC and vice versa. Hmm. [Update: Transformers may be part of a circuit that converts AC to DC, but they cannot do so alone.]

But even the more boring electronic components can make noise under the right circumstances: resistors, capacitors, you name it. Throw enough energy through these tiny bundles of conductors and insulators and yes, Virginia, they can start to vibrate. Vibration == motion == noise!