Question Cracking sound when I flipped the PSU switch on/off

[SkildX]

Hi, I have a question. I just bought a Seasonic SGX-650 2 months ago. When I flipped the switch to turn off the PSU, I heard a short cracking noise. It was the same noise I heard on my previous PSU Seasonic S12-III. Is the cracking noise normal? It doesn't happen all the time BTW and the PC still boots; I'm using it right now. The PC is connected into an APC UPS. I cannot tell if what I saw was a spark on the PSU or it was my ethernet blinking since I was looking at the top of my PC when it happened.

 

[--SID--]

Inrush current probably.

Do you turn on and off the PSU with the switch daily?

 

[SkildX]

Inrush current probably.

Do you turn on and off the PSU with the switch daily?

No. I usually leave the switch at ON position. I just turn on or off the UPS only. I flipped the switch to turn off the PSU and unplugged the PSU cord to avoid ESD since I was doing a quick maintenance, and then I heard the crack. And the outlet is not grounded because there are only 2 wires on the wall outlet; no wire for ground.