Weird 1U PSU noise when plugged in
Hi guys, I got this modded 1U PSU (Delta DPS-500AB Platinum) which makes a weird noise when it's plugged in but PC is off. When the PC is turned on the noise is gone.
Video link: https://photos.app.goo.gl/m8CahnDNsWV1C1xX8
The modder insists that it is normal. To quote (translated from Chinese): "It is the working sound of the switching transformer. This is the case for all 500W models".
I have never heard this kind of noise from the previous PSUs I owned. I am hoping some of you guys who are knowledgeable/experienced with PSU's can chime in. I wonder if this is really normal or is it actually a faulty PSU. And of course, whether is it safe to use.