High Pitched Noise

Hard drive or fan. Capacitors are silent.

Nothing is connected to the motherboard except for the PSU. I think bad capacitors make noise, but I'm not sure.

Well, perhaps take the insert of apaper towel roll and place it to your ear then down into the case and try to locate the source of the noise. Point it to the PSU also.

ok, I'll try that.

It is definitely the motherboard.

Does the CPU have a fan?

no
(edit: it has a big heatsink)

Well, a MB is silent. So, a fan or hard drive are the things that make noise in a computer. I suppose a DVD/CD player making noise is possible. MB has no moving parts. Also, video cards have fans that can make noise.

I have experienced what you are referring to with my graphics card (4870x2), I know the sound of my fan (and manually set it) I know its not that for me, but when my frame rates get excessively high (in some menus they peak at between 1200fps and 2200fps), I get a very high pitched sequel which goes away after going back to the game (where it has real work to do).
It is not coming through my speakers, it emits from the card itself.
I wish I knew what it was so I could advise, sorry.

high-pitched noise are caused by some component distorting the natural wave form created by clock generators or power regulator. With computer, the regulators are mostly to create the noise. A componant failing in the electronic regulation circuit may cause sinewave chopping and creating right angle in the wave and too much of these right angle may cause vibration in the circuit.

Well, as I can see clearly the phenomen in my head, it is in fact really hard to explain if you don't have electronic notion..

A poster wrote, simply, "capacitors are silent."

To which I reply, equally simply, "Some types of capacitors can be noisy."

Capacitors used in _bypass_ service--service in which the capacitor is used to shunt electrical noise and unwanted signals to circuit common (chassis/"ground"), commonly use a ceramic _dielectric_ (insulator) that exhibits _piezoelectric_ properties. A piezoelectric substance becomes electrically charged when physically deformed or--acting in the other direction, so to speak--becomes physically deformed when subjected to an electric charge. It's the "applied voltage causes physical deformation" aspect of piezolectricity that allows ceramic bypass capacitors to act as miniature speakers, transducing some of the electrical noise they're carrying to _acoustic_ noise--that is, actual sound. (That ceramic capacitors can also act as microphones causes other sorts of problems in sensitive circuitry used in other branches of electrical and electronic engineering.)

So it's quite common that circuit boards that include multiple ceramic bypass capacitors and are busy with digital signals--and computer motherboards and graphics cards certainly fit that discription--may emit clicks, chirps, buzzes, whines, and'/or hisses depending on what their bypass capacitors are handling.

Best regards,

David Newkirk
DavidNewkirk@gmail.com

I am sure it is motherboard because I had a similar issue... I sold my motherboard not go get deaf because the noise was always with me when I left the computer. Tried everything from changing the PSU to removing all parts in order to specify the component where the noise is coming from... Pretty sure I am it was 1 or more capacitors... This even happens in newest motherboards... This also depends on your hearing ability.. Another friend of mine never got disturbed from the same noise

I am also pretty angry when people write about motherboards not having moving parts.. damn I disconnected every single fan, HD .. GPU... even CPU fan... the noise was there.... so something moves in motherboard which we can not see with our eyes.. it is move of electrons which cause noise somewhere...

if the noise does not disturb you live with it... if not sell it and get another one like I did...