|Disconnect the power. That'll stop the noise.|
Honestly. A CPU is a processing chip on the motherboard. The only time I've ever heard one make a noise was when it crackled while letting the smoke out.
If you have noise coming out of your COMPUTER and you want help fixing it then you need to give a full description of your system and try to describe the type of noise.
Is it a buzz, a beep, a whirr, a tap, a knock or Lady Gaga
Goin' Fishin' (Some day)