We have a laptop which randomly beeps. Three beeps. We have solved the problem but in case others have it, here is the description.

It is a HP EliteBook 9480m running Windows 7 (but that is not relevant).

We had HP change the Battery, Keyboard, mainboard and more. Still beeps. Booted into Safe mode, beeps.
Run all kinds of HP diagnostics, nothing appears to be wrong. Imaged the contents to another EliteBook 9480m laptop. It does not beep.

Back to the beeping laptop, uninstall any HP software (It was a fresh Windows install). Still beeps.

Tested the beep character at the command line, it sounds different. Tested the beep through the sound card, it sounds different. It sounds like a BIOS default beep.

Disable the Beep device and the sound card. Still beeps.

Started to listen to where it was coming from, there are no speakers near there.

It was the hard disk. If you listen very carefully you could hear a short mechanical sound and then Beep. The beep sounds so much like a BIOS beep, we were totally onto the wrong track. Does the hard disk have a tiny speaker ? Doubt it. I suspect the arm in the hard drive is making a noise that sounds like a beep.

how weird.

Now I look online knowing this and find many others point to the hard disk.

I guess after the fact, it is always easier to google and find answers, knowing the final fault 🙂