HP ProBook 450 G8 High-pitched noise when powered off

[mba15]

Hello,

this 'problem' is with my HP Probook 450 G8 I have had for about 8 months now. 

Just recently I noticed the laptop produces a subtle high-pitched noise, similar to an endless electronic beep, which is produced ONLY when the laptop is powered off. I have no idea whether this is something I should be worried about or when this sound first appeared. It also doesn't seem to be a software issue, as the sound only occurs while the laptop is powered off and still persists after a BIOS firmware update last night.

PC specs:

HP Probook 450 G8 - i5-1135G7 - Intel Iris Xe- 8GB RAM - 500GB SSD - WIndows 11 Pro 21H2

The laptop was brand new when I got it, and is still in pristine condition. I have not replaced any parts or even opened its back as of yet. The laptop has also not experienced any water spills, physical damage or power surges. 

Here's what I can tell about the sound:

1. The noise sounds like an endless high-pitched beep. It is barely noticeable normally, but clearly heard when in a silent environment or when the bottom of the laptop is held close to the ear, although I couldn't tell from which area specifically it was being emitted. It is also a bit louder than the laptop fans operating under no load.
2. There is no abnormal sound while the laptop is turned on or on standby, but after I shutdown or hibernate the laptop, it appears a few seconds later.
3. When any key is pressed on the keyboard while the noise is 'on' (laptop is off), the sound disappears for a second then reappears. Holding down a key makes it disappear for a bit longer, before it reappears, and pressing the same key again doesn't do anything unless a different key is pressed first.
4. Upon hard resetting the laptop by holding down the power button for 15 seconds, the sound disappears for a few seconds before appearing again.
5. Plugging in the charger and switching it on makes the noise stop, reappearing as soon as I stop charging/unplug it.
6. The sound started when I shutdown the laptop at night, disappeared momentarily after a hard reset, and could still be heard when I checked in the morning.

The closest thing I could find was this [content removed], which states similar case for an Acer laptop, although I'm not sure if I have the same issue.

I would appreciate if somebody could help me understand what is causing this sound.

Also, should I be worried about it, and if so, what needs to be done to solve it?

[nicon963]

Noise came from ec prom in motherboard. I think that hapening after bios update from 01.03.01 to new one

[mba15]

Had the motherboard replaced... original issue remains unresolved, got more issues instead. 

Will take it back and see if they can figure out what the problem is.

[nicon963]

I have hp 440 g8, it is weird. I think that many people dont solved it.

[mba15 · Accepted solution]

When the sound persisted even after a board replacement, I asked the Service Center to inquire with HP, and they sent me the picture below.

I had first tried to inquire with HP Support. Unfortunately, HP does not provide direct customer support in my region.

All of this hassle could have been avoided if an HP Customer Support Representative had simply informed me of the RESOLUTION in the picture above, instead of sending me a link for nearby Authorized Service Centers.

Thanks HP.