High Pitched Noise in Computer

[Oren10]

Hi,
Whenever I boot my computer it makes a high pitch humming noise. I thought that it was speakers but one day I disconnected them and still the noise is there. I am have an old p4 machine with 1GB ram. There is a 160 Gb hard drive with an LG DVD writer. Everything is out of warranty. I do not understand the exact cause of this problem. Is any part of my system is damaged. I worry about this. Please help.

[Hardwareman]

The noise is produced by the moving parts in the system. It can probably your psu. The power supply units contains a fan inside it. It is possible that the power supply is gone. As in the old pc the power supply creates such sound. Change the power supply of the system. Because an damaged power supply can fry up your motherboard and other devices.

[Maxforu]

In my system the cause of sound was hard disk. When the spindle motor in the mid of hard drive becomes old it produces a humming sound. It denotes that the life of your hard drive is over and you will need to now back up your data. Do one thing disconnect the hard disk and boot the computer. If you cannot here the noise then it is definitely a hard drive issue.
Extremely high noise level
CPU fan making noise

[Killen]

Is there any cd leaved in your dvd drive. Just first check it out. It can be disc. Because whenever the system boots up it check out the media in the drive if it is configured in bios. The rotation of disc creates the humming sound. If not then open up your tower and remove all the connection to hard drive and dvd drive. Then boot the system. If the noise is absent that means it is coming from the hard disk otherwise your power supply is gone. CPU fan can also be issue for that. Try to change the fan and check out.