[SOLVED] My PC got dropped and now it makes a loud high pitched whine when plugged in

Jan 31, 2019
I recently moved to a new place and accidentally slammed my PC onto the floor pretty hard while I was putting it down. It still works, but now when I plug it in, I hear a very loud high pitched tone, like a mosquito, or what you'd sometimes hear from a big CRT TV. I can hear this sound even when the computer's turned off, as long as it's plugged in. It takes about five seconds to stop after unplugging. It seems to get a little more quiet when the PC is actually on, although that might just be because the sound of fans masks the noise.

I understand it's most likely coil whine, and the common sources of inductor coil whine are the PSU and the GPU. I disconnected the graphics cards and the sound was still there, so they're not the source of the sound. But I tried to use screwdrivers and paper tubes as stethoscopes and couldn't isolate the source of the noise. It seems like the noise might be coming from the motherboard itself. So I disconnected the ATX power connector from the motherboard and plugged it in again (was this stupid? not sure) and the whine was still present but much quieter. I never plugged in the PSU without a motherboard before, so maybe it always would have made a faint sound even before I dropped it.

So my problem is: I can't tell for sure if the PSU is the actual problem. The most likely thing is that dropping the case damaged the PSU and that's the only thing I need to replace. The motherboard draws a little bit of power even when turned off, so that draw could be making the sound worse. But maybe the motherboard or some other component was damaged in such a way that it's drawing power unsteadily and that's what's causing the whine. Even if the PSU is the source of the noise, which I'm not sure is true, couldn't the whine be caused by an electrical problem elsewhere? That could also explain why the noise got quieter after disconnecting the motherboard.

In short, how do I determine whether or not I just need a new PSU?

Thanks for your help.

Update: I got a new PSU and the issue is gone. Motherboard is fine.