Motherboard beeps continuously as soon as PC is powered on but PC works fine - video

[electricsix]

I've got a new PC that I built 3 months ago. It's been working fine up until last night.

Last night when I shut down the PC, it started beeping rapidly for a few seconds until the computer was completely off. I rebooted and there were no issues.

Today I powered on the PC and the instant that I touch the power on button the PC started beeping rapidly. It doesn't stop although the machine runs and works as normal. The beep is so distracting that I can't use the PC, even though it works.

I've tried disconnecting the internal speaker but this makes no difference.

The mobo is a MSI B350. No lights show up on the EZ diagnostic sensors.

What I've tried:

1) Disconnecting internal speaker - no difference
2) Removing graphics card - no difference
3) Removed all peripherals - no difference (so it isn't a stuck key)
4) Removed and re-seated RAM - no difference
5) Checked every single connection to the mobo

Build is as follows:

Ryzen 5 1600x
MSI B350 mobo
8gb DDR4 RAM
GTX1050ti 4gb
250gb SSD
1 TB & 320 gb HDD
OS is dual-boot Linux Mint/Win 10

The system still runs and works fine apart from the beeping. The beeping starts instantly as soon as I nudge the power button and continues right until shut down. The only thing different about my PC is that I moved it yesterday, so I guess something may have moved internally but I can't identify it.

Any suggestions, or at least any way I can disable the onboard mobo sound?

EDIT: Made a quick YT video here: https://www.youtube.com/watch?v=bcvqf4w7pqY

Apologies for the poor picture quality, it's really dark in the room where my PC is.

 

[electricsix]

Problem fixed:

The beeping was coming from the display unit inside the front of the case (Atrix a9001-c4 for anyone who lands here by Google one day). The problem was not with the motherboard but with the temp/fan speed/time display on the front of the case.

I disconnected all the cables that linked the case display to the mobo (Power switch, speaker, Firewire, USB, reset switch, audio jack, HDD light) but the problem still persisted.

I then noticed there were two other 3-pin fan connectors running from the display case and connected to a spare molex connector inside the PC. The fan pins aren't connected to the mobo (not compatible) but they were still drawing voltage to power the display on the front of the case.

I guess the temp/fan speed display on the display case was expecting a signal from the motherboard about fan speed or temperature but not getting one and so sounded the alarm on startup. No idea why this only started now but at least it's fixed.

Solution was to disconnect the fan cables from a power source and the beeping immediately stopped. It means that the display on the front won't work but I've never used it in 11 years (new build, old case) any way so won't miss it now.