Buzzing Noise from iMac 27'

Got buzzing noise from top left corner, and very hard to turn on, power button may or may not response.

The fan noise also comes from bottom right corner, thinking to replace a new one.

Issues

The power button got issue long ago, sometimes can not work, sometimes can. I think after disconnected from power, maybe will be ok later. I thought it could be bottom connection issue.

After moved iMac into a quiet room, I heard buzzing noise from top left corner, I started believe the power supply got issue.

Plan

Replace power supply later together with fan.

References

IMAC Buzzing Noise From Top Left Corner FIXED!! / Replace Power Supply