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For a while my computer have been making a electric leak like sound whenever the CPU usage gets high. However, lately it started to make it more often. For example with anti-virus searches and malware search softwares, the CPU usage goes up to 80 percent and this weird noise comes from the CPU.

This sound sample i have recorded for you to picture the sound. This was recorded with microphone very near to CPU. The background humming noise comes from the fan, but I am very certain that this leak-like sound does not come from fan because it does not have a specific pattern and only occur with high CPU uges. The CPU usage was around 80% in this recording.

For information, my configurations are:

Intel Pentium 4 CPU 3.00 GHz 2 GB RAM
Motherboard MSI 915P/G Neo2 Platinium ed.

so not that bad.

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up vote 1 down vote accepted

I'm 90% sure it's the fan making the noise as it sounds in sync with the airflow. I recently turned a retired desktop in my house into a Ubuntu Server (Samba shares, local IM, Print server, headless VM, etc...). At night when it was quiet I started hearing a chirping sound, as if a bird was stuck somewhere. It would chirp a couple times, and stop. A couple seconds-minutes would go by and it would do it again. It took me a while to locate the sound and realize the CPU fan was the culprit. Never underestimate the weird sounds your PC can make.

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Have not heard the sound yet but I am very certain that the 'CPU' -- as in the processor chip -- does not make any sound.
If it 'sizzled' it would burn out and die; but, before that it would trip the power and shutdown.

The only other occasional sound that comes to mind is the one from some hard-disks.
Note that high processor activity is usually coupled with high disk activity.

Update: Ok, I got curious about this 'CPU Whine' descriptions mentioned by Arjan & Marcin.
Seems like there is a specific case with processors that support power management.
It is described to some extent in this Dell Tech Support article. Journal ID: 10019BMDJ8, Article ID: 295216

In certain situations, an intermittent, high-frequency buzzing noise may be heard from the system. It appears to change with processor activity and can increase in frequency if USB devices are attached.

This buzzing noise is apparent to some degree on all laptops but is perceived as abnormal because it is different from the other more familiar noises the computer makes.

The noise has been isolated to the processor’s power circuit and is only audible when the processor is in C3 (clock-stopped) power state. In this state, the computer is in a low-power mode designed to reduce chassis heat and extend the battery life. The changes to the components in the processor's power circuit are caused by a phenomenon referred to as the Piezoelectric Effect. When a specific voltage is applied to these components, they begin to resonate producing sounds that fall within the range of human hearing (15 – 20 KHz).

The noise is normal and within the acoustic specifications of the computer.

That article then goes on to describe how to disable the C3 clock-stopping as a workaround.
Note that 15-20 Hz is quite low frequencies.

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Your answer may very well be correct for this situation, but just in case you're trying to say that a processor never makes any sound: unfortunately, "cpu whine" is not too uncommon -- (sometimes only occurring when the processor is not very busy) – Arjan Jan 17 '10 at 23:39
CPU Whine is usually not the CPU at all. The reason the whine usually happens when the processor is idle is because the capacitors are at full charge. It is the capacitors making the sound. – Marcin Jan 18 '10 at 0:51
@Marcin and @nik: thanks for that info. I guess I was totally misled by the name "cpu whine". (Too bad Dell thinks "The noise is normal", just like Apple did for their MacBooks. The high-pitched whine can really drive one crazy...) – Arjan Jan 19 '10 at 13:59

I can't really tell anything by that MP3 file, but "Zappy" noises usually come from failing components in the power supply. The more CPU (etc) you use, the more strain on the power supply, so the zapping may increase under load.

You may also want to check the CPU and chassis fans for stuff stuck in them that may be causing the noise (take a can of compressed air to them). Dirty fan bearings can kind of sound like elecrical buzzing, so if you can stop each fan for a second while it's running (without cutting the tip of your finger off), that will help you eliminate them.

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Its most likely the fan on the CPU making this noise. Some very cheap fans use sleeve bearings which wear out after a few years of running. You'll need to get that replaced.

The heatsink on top of the CPU may also be full of dust. I was servicing an old server and found out that the CPU fans would immediately speed up to around 70% as soon as a terminal server user logged in. Turns out that cleaning the dust out from the fans and the case were the answer.

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