Why my pc when I put a plug on it just turn on automatically.

Hi!

The light and beeps are diagnostic codes.

For interpreting the diagnostic codes, please see the Interpreting system validation diagnostic front panel LEDs andaudible codes section in the your service manual. Take note of what diagnostic code you're receiving and update us and well see how we can further assist you.

If the diagnostic codes are not of help, please check the if you need to replace the cmos battery. An old cmos battery can sometimes cause strange problems. Here is the guide section for removing the cmos battery. I would also ask you to reset your bios settings, but this will also be achieved by pulling out the cmos battery. Note, by removing the cmos battery your BIOS settings will be reset to factory default, any changes will be lost!
For testing your cmos battery I'd use a multimeter, and according to the service manual the battery are to be around 3 volts. If you are unable to check the voltage of the cmos battery, I'd recommend replacing it anyway as they tend to be pretty cheap and can be found in most stores. To know which model of coin cell battery you need, check the model text on your battery.

Please respond once you've looked at the above instruction.

Good luck,

Cheers