component noise

[skymaster]

I experience the following with my notebook (P4 1.6, Intel 845MP chipset, ati M7, brand compaq, model evo n800)
In certain circumstances noises are emitted, not from HD, fans or speakers. So I'm wondering what could be causing them (as there are no other moving parts). The noises occur when:
*processor is under full load: fairly high-pitched, but varying with what gets displayed on screen, sometimes ceasing briefly.
*viewing sites with java applets: high-pitched sound, very annoying
*running acrobat.exe: lower pitched, buzzing
Intensity lowers when running on battery. Noise stops when clicking on exit cross and holding button down. Restarts when releasing (without closing the window).
That's it. I'm puzzled. Everyone is surprised. Let me know if you have the same issue or know the answer!
Oh yeah, and the fan, when it's on, has some sort of rythm to it, but that's a different issue.

 

[HammerBot]

The high pitched sound is sub-harmonics of the switching frequency of the switchmode powersupply. Usually these are inaudible. But the fact you can hear them suggest a poor design (e.g. insufficient decoupling, too low switching frequency etc.) or a failing switching transistor. The rhytm in the fan is probably also related to the power.