CPU makes high-pitched noise

I have a VIA C3 533MHz fanless CPU. I'm using it as a server. However,
when the CPU starts to do something, it emits a high-pitched noise.
It's not loud, but noticeable. I can handle it -- it's no louder than
my PC fans. But I'm curious as to why it's happening, and if I can stop
it.

I've ruled out everything else but the CPU/mobo. I've unplugged the
harddrive, but it's still making the noise. The CPU (obviously) has no
fans, and neither does the PC. It's not the PSU, as I've used it before
on a much beefier system (this one uses about 15W total) with no
problems.

If the CPU is idling, however, there is no noise.

Anyone have a clue?

anonymous_c <mccpat RemoveThis @gmail.com> wrote in part:
> I have a VIA C3 533MHz fanless CPU. I'm using it as a
> server. However, when the CPU starts to do something, it
> emits a high-pitched noise. It's not loud, but noticeable. I
> can handle it -- it's no louder than my PC fans. But I'm
> curious as to why it's happening, and if I can stop it.

> I've ruled out everything else but the CPU/mobo. I've
> unplugged the harddrive, but it's still making the noise. The
> CPU (obviously) has no fans, and neither does the PC. It's
> not the PSU, as I've used it before on a much beefier system
> (this one uses about 15W total) with no problems.

Most likely the mobo powersupply regulators/inductors.
They can switch at high-audible ranges.

> If the CPU is idling, however, there is no noise.

Powersavings.

-- Robert