I would start the troubleshooting by disconnecting the second S3422DW and all of its cabling from the PC. Then test the first S3422DW by itself. When done testing, replace the single first S3422DW with the second S3422DW and retest. In these single monitor setups, does the random high pitched noise happen?

Each monitor is located in a different room and I only use them individually with my windows 10 laptop. My partner uses the other monitor with a different windows 10 laptop and experiences the same issue. We have tried swapping monitors but this hasn't made any difference.

I have the same problem with the same monitor, since new (one month old now), so would be interested to know what the solution is too...

I've tried several HDMI and Displayport cables. I can stop the noise by adjusting the volume control in Windows taskbar but the noise comes back again after a while.

What else I can attempt to resolve the issue with each of my monitors as they are only used independently?

Thanks,
Jeff

I have the same problem with my newly bought S3422DW. I haven't successfully find any solution or explanation on this issue on Google. 

I'm afraid I'm going to return the monitor to DELL and request a refund.

I have the same problem. Dell has sent me a 2 new monitors and each of them has the same issue. I've tried to use low frequency protection in the sound settings, however that did not help. I'm afraid I'm going to return the monitor to DELL and request a refund.

Update = I've tried the monitor at my parents house with another computer and I didn't have this high pitched noise. So, I think that problem might be related either to my computers or some local setting. It's really strange and hard to understand.

I have also had the same problem with my S3422DW (in Australia) which is only a few months old. Problem started within a month.

The only solution I've found to reduce the frequency of the noise occurring is to decrease the brightness, but that is not ideal.

I'm also going to be contacting Dell about a replacement or refund

Thank you for posting this. It is still unresolved as of 12/6/2021. I have the same display. I run it in its native resolution of 3,440 x 1,440. I am having this issue where at random times, the display emits a high pitched "whine", like a dog whistle that a human can hear. I recorded it. It is extremely annoying to the point where it distracts from my work. At first, I thought maybe it was a cable issue. I have confirmed this issue both with HDMI and Display Port cables. Then I attempted to change the frequency from 60-100 Hz. Then I factory reset the display (thinking maybe a combination of brightness, contrast, sharpness, or audio level caused the issue). I confirmed this occurs with Mac OS, Windows 11, and Windows 10. I have the latest drivers from Dell and all systems are up to speed with System Updates. I'm unable to predict when this will occur nor can I determine why it does. I contacted Dell as this display is only 1 week old and they have issued a replacement. I will post back here on this thread if the replacement device emits the same issue. I hope it is a random occurrence because the display is beautiful, the speakers pretty good, and I don't want to have to return it entirely and start my search for a display replacement all over.

Hi,

Exactly same problem here with a just buy one.

Any solution found since last message ?

Can an exchange improve that or all the series is definitively affected ?

Thanks,

Remy