[Bloody Sam Roberts]

I know capacitors can buzz, but isn't that usually when they need to be replaced?

They can emit noise but that is usually in the 5 to 10 milliseconds before the tops dome up and the thing craps out.
I'm at a loss to explain how a cap could "whine".

[mowowie]

One of the Caps on my motherboard whines when I overclock the proccesor.

[Swordmaker]

Re: whining caps.

Back in the days of foil and paper capacitors it was not uncommon to get a whine when the paper was holed and there was arcing through.