hey, im no engineer, but i can diagnose a problem when i see/hear/experience it.
Well ... not precisely

- you are experiencing something but you are not
exactly diagnosing it - you are assuming an explanation
- no scrolling in Safari - computer doesnt make a noise..
...
a few of those links indicate capacitor whine, or faulty fans etc. but it doesnt sound like them at all.
Simplifying things a bit it is impossible for a capacitor to make whining sound.
For those interested more detailed explanation of this issue:
Modern digital electronics (especially computers) use big, power hungry chips like CPU or GPU. Chips like that in order to keep the power dissipation at bay must be powered using lowest possible voltages (because P = U x I).
This means that designer of the system needs several stabilised rails capable of delivering literally tens of amps at few volts. The name of the game here is miniaturisation and efficiency so virtually all of them use something called step-down DC converter (
http://en.wikipedia.org/wiki/DC-to-DC_converter).
To design step-down converter which is small and efficient will in 99% of the cases mean switch-mode conversion with an inductor which stores the input energy temporarily and then releases that energy to the output at a different voltage. This is usually done at frequencies ranging from hundreds of kHz to several MHz.
Often there is more than one, with some really hungry chips (like GPU) having dedicated converter/stabiliser.
Finally we are arriving at the issue at hand:
Properly designed and built switching mode magnetic converter will be inaudible.
Unfortunately in real life this is not always the case, and many of them will
make whining sound from the inductor when the converter is not built (or designed) perfectly. Usually inaudible hum is due to vibration of windings in the inductor and/or magnetostriction.
This is especially true when switched mode converter is not loaded because it then operates at the lowest frequency (which in extreme cases could be straight in the top of audible human range).
The only possible fix for the issue is to replace the inductor ... not something
which could be recommended to an average person.
All of the above is greatly simplified, but the bottom line is (like DoFoT9 rightly pointed out) that we all have to leave with it.