Electrical buzz when PC and monitor connected on the same circuit

[tsomerville93]

Hi folks, I've got a bit of a bizarre problem.

I've just built a new system but retained the PSU, SSDs and screen from my old build.

The system works perfectly albeit for a high-pitched buzz (not dissimilar to coil whine; sounds like crickets in the night) coming from the PSU and the monitor's power adaptor simultaneously. I recorded the sound here: https://www.youtube.com/watch?v=F3Ffmp4ZvIw

In the video, I've separated the screen and the PSU so that I could try and isolate the source of the noise.

It only occurs when the monitor is turned on, and doesn't appear to be affected by GPU or CPU usage. I noticed no variation in pitch or volume while bench-marking GTA V and Far Cry 5.

The noise is also present even if the monitor is not connected via HDMI to the PC. I've tried turning the monitor on in the hallway and having the PC on in the bedroom (same circuit) and the noise is still present.

If I connect the monitor to my laptop and turn the PC off, the noise isn't present. It seems like the combination of the PSU and monitor power adaptor causing the noise.

Here's other things I've tried while trying to isolate the problem:

• using the HDMI output for the motherboard instead of the GPU (as seen in video - no change in noise levels)
  
  
• running the PC without the GPU (no change in noise levels)
  
  
• adjusting the brightness of the display (the lower the brightness, the lower the pitch of the noise)
  
  
• using the display with a different PC (no noise at all)
  
  
• rebuilding the system from scratch and checking all connections (issue reoccurs)
  
  
• turning the monitor off (the noise instantly stops)
  
  
• using a different HDMI cable (noise persists)
  
  
• using a different power cable (noise persists)
  
  
• using the TV instead of my monitor (noise stops)
  
  
• running the PC and monitor on different circuits in the house (noise stops)

The most puzzling thing is that this problem was not present during my old build, which included the very same screen and PSU combination. I've tried to isolate the problem further by just running the system with 1 RAM stick, the CPU and motherboard but the noise persists so I am doubtful that the GPU is to blame.

Apart from picking up another screen or PSU to test different combinations, has anybody got any tips or ideas for the cause of this issue?



System Specs:

AMD Ryzen 3600

NVIDIA 1660 Super (MSI Gaming X)

Gigabyte Aorus B450 Pro Wifi

Corsair AX760


Many thanks!

 

[EsaT]

How old is that monitor?
Maybe it's tiring and keeping it connected to wall kept it going normally and being out of power during PC rebuilt made it cool and start some interference.
Especially cheaper monitors are unlikely to have as good input filter, whose job is as much to prevent power supply from sending interference into power line

As for solving it putting some APC/Belkin surge arrester in between monitor and computer could stop it.
Those have EMI/RFI filter in them