Motherboard whistling near the processor

[solarkey]

Recently noticed a strange whistling noise in my laptop. It happens when the laptop is turned off and the power is connected. (charger or battery). This goes in the area where the processor is located. HP diagnostics, bios updates, driver updates did not help. What could it be? Is it normal?

[Huffer]

It's called coil whine and it is unfortunately not common but occurs in computer hardware sometimes. Here is an explanation:

https://forums.tomshardware.com/threads/coil-whine-after-installing-new-ram-and-cpu.3785257/

This article suggests making some adjustments in the BIOS that you cannot do on an HP laptop. There is discussion about the effect of power kicking in. Good luck with it. 

[solarkey]

Is that a critical issue? Do I have to fix it? Or is it easier to leave it as it is?

[Huffer]

Will not harm the computer but OMG its annoying. If you read the thread I linked it suggests changing the battery might help. I got rid of the only computer I ever had of dozens I have owned that developed a coil whine.