Hello everyone! So I recently built a new pc by myself, the first one I've built too. I've had it since about August. It has been performing wonderfully with no problems at all, until today when I was trying to connect a USB peripheral when I noticed there was a high-frequency noise coming from my PSU. It is very silent I can only hear it when I put my head next to the PSU. I've had this problem in the past with my old pc, which I bought already built, but it had a crappy Chinese PSU. But the noise was coming from it when the computer was turned on, but with my current pc, the noise is coming when the computer is turned off. I have a Corsair TX-M Series 750W PSU. I was already researching about it on the internet, but I found only that the problem was because the PSU was not 80+ certified, but mine is 80+ gold. Which means it should be good quality, right? Anyway, I will specify all of the stuff, that could affect it, So the first thing is that the pc has already turned off 3 times because of a power outage, the first 2 times it was a brownout, unfortunately, the first brownout happened and then I turned it on to check if everything was alright and then a few minutes later it happened again. And the third time was recently when the power disappeared due to a snow storm. I've been trying to get an ups, but currently, I just don't have the money. The second thing is that I have a led strip in the pc which is on top of a PSU shroud. And then the final thing which I think would affect it is that I have a feature on my motherboard, when the pc is turned off it still supplies power to the USB ports, I've been trying to turn the feature off, but I haven't found an option, so in the meantime, I just use a USB hub with a switch, because when I turn off the pc my keyboard and mouse are still lighting up.