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Certain mechanical components of a computer produce noise, such as speakers, fans, harddrives and disk readers.

Can electronic components of a computer (transistors, resistors, capacitors, ICs, screens, power supplies, etc.) also produce noise, or is noise limited to the realm of mechanics?

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    \$\begingroup\$ Some ceramic capacitors can have a piezoelectric effect and start to make noise. Also, see this related question. \$\endgroup\$
    – m.Alin
    Commented Jul 28, 2012 at 15:08
  • \$\begingroup\$ If your computer is old enough it uses relays for its logic circuits. Thousands of relays switching at once makes a lot of noise! \$\endgroup\$
    – pipe
    Commented Nov 30, 2015 at 5:07

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Aside from the obvious components (speakers, motors, fans, relays, etc.) it is quite common for inductors, transformers, and capacitors to make noise.

Inductors and transformers work by converting electricity into magnetic fields. Sometimes these fields are moving/vibrating/whatever in just the right way to make parts of the inductor or transformer to mechanically vibrate and make audible noise.

Capacitors are just two metal plates separated by a non-conducting material (a.k.a. dielectric) so it seems like there is nothing to vibrate. But, it can! Some materials are piezo-electric. Meaning that when they are exposed to an electric charge they change their physical shape. This is how piezo-buzzers work. Some capacitors use a piezo-electric material as the dielectric. As the caps charge and discharge they change shape. If this happens at the right frequency and power you can hear it.

There are probably other components that can cause audible noise, but these are the most common.

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Yes, components can produce noise.

Common noise producers are coils and capacitors.
Magnetostriction for coils (i.e. inductors/transformers) and Piezoelectricity for (ceramic) capacitors are the reasons.
These effects cause the component to change shape ever so slightly, and if the applied frequency is in the audio range we can hear it as a buzz.

This is why you can often hear a high pitch whine in an SMPS power supply (an ATX supply is an SMPS supply)

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  • \$\begingroup\$ Any idea on how to capture them? Or perhaps a program or a utility that could read them? \$\endgroup\$ Commented Apr 12, 2019 at 16:11
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Acoustic noise from inductor windings can occur even when potted in epoxy if the current surges produce energy in the audio range.

Large Power Station transformers that handle thousands of amps in residential neighbourhoods may emit acoustic noise based on the fundamental and harmonics of resonance. In some cases noise cancellation audio systems are used reduce hum and thus eliminate noise from consumer complaints.

Likewise microwave ovens resonate from the high peak currents in the magnetronic and vibration of components.

Every component has an acoustic resonance but the rigidity of placement on the assembly reduces the chances of vibration. Often you may find large components firmly attached in power supplies with polyurethane blobs to prevent vibration.

Wire wound resistors in ceramic can be made to resonate with enough energy pulsed at an acoustic rate depending on how close to physical resonance or harmonics.

Since rigidity of electronic components is essential prevent fatigue, any parts which do make noise may fail more rapidly.

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    \$\begingroup\$ The big blobs of glue on large components in power supplies is indeed there to prevent vibration-- but vibration from shipping and bumps. Large components often have large mass and are prone to flopping back and forth during shipping and need to be fastened/fixed/tied-down to avoid snapping off due to metal fatigue. This glue does little to nothing to prevent acoustic noise from the components vibrating during normal use. \$\endgroup\$
    – user3624
    Commented Jul 29, 2012 at 16:28

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