When you start your computer, the speaker has a tweet.

When the user is using the computer, the computer starts normally, but the speaker makes a shrill tweet.

This situation should first check the sound card and the speaker cable has no shielding line, or the line is not grounded. Also check whether for the motherboard, sound card and other electromagnetic radiation caused. Whether the host power supply has high-frequency oscillation signal.

You can shorten the connection line of your sound card and speakers and plug the sound card into a slot away from the video card. If both of these methods do not solve the problem, you can test the replacement power supply.