On Sat, 23 Jan 2010 10:48:50 EST, Justin Piszcz said:
> Hi,
> 
> Linux:
> When I do not load the ACPI processor module, there is no high pitch 
> noise.  When I load the ACPI processor module (so I can utilize Turbo 
> Boost), Linux makes the system emit a high pitch noise.

Sounds like singing capacitors.

http://lwn.net/Articles/145973/ - and see the last 2 comments.