Question PSU buzzing for 5 minutes after turning it off and removing the power cable from the PSU?

[MFaze]

Bronze PSU: MWE Bronze 750 V3 230V

My motherboard was damaged because I accidentally inserted my SSD in while my PC was still on. Wanted to test the motherboard with separate components so I switched out my plat PSU to the bronze PSU and also switched my CPU.

After testing, I realised that the motherboard had damaged my 2nd CPU during testing. Now I'm afraid that it might have damaged my bronze PSU too.

Before, I never really noticed any kind of buzzing when entering bios, but after testing it with my damaged motherboard, I noticed that even without turning on my 2nd motherboard its still buzzing. After turning off the switch on the PSU, removing every PSU cable from the GPU and motherboard, removing the power cable from the PSU and power socket, it was still buzzing for 5 minutes before slowly dying down.

From my understanding, coil whine only happens under load or when the computer is on, but my bronze PSU still buzzing after removing any kind of power source.

Is this normal or should I buy a new PSU?

Update:
current system spec in picture
PSU : MWE Bronze 750 V3 230V
Motherboard: B450I GAMING PLUS MAX WIFI
CPU : Ryzen 5 3600
Storage: no SSD or HDD
Ram: no ram
OS: no OS

 

[Ralston18]

Not normal.

The buzzing might be being caused by a capacitor slowly discharging and thus ends once the capacitor has drained.

More needs to be known.

Update your post to include full system hardware specs and OS information.

Include disk drive(s): make, model, capacity, how full?

= = = =

Nor cam I rule out power reaching your system via some other path that does not include the PSU's power cord.

Other connected devices? If so how are those devices connected and what are their respective power sources?

Are you using any power strips or surge protectors?

 

[MFaze]

Not normal.

The buzzing might be being caused by a capacitor slowly discharging and thus ends once the capacitor has drained.

More needs to be known.

Update your post to include full system hardware specs and OS information.

Include disk drive(s): make, model, capacity, how full?

= = = =

Nor cam I rule out power reaching your system via some other path that does not include the PSU's power cord.

Other connected devices? If so how are those devices connected and what are their respective power sources?

Are you using any power strips or surge protectors?

Updated my post with my specs in the picture.
current system spec in picture :
PSU : MWE Bronze 750 V3 230V
Motherboard: B450I GAMING PLUS MAX WIFI
CPU : Ryzen 5 3600
Storage: no SSD or HDD
Ram: no ram
OS: no OS

There's no other connected devices,

The power extension that I used to connect my PSU's power cord does have surge protector