Onboard sound card is getting interference after adding DisplayPort monitor.

[cf18]

And it's not any "ground loop" thing since it affects the S/PDIF optical out.

Hardware/OS:
i5-6600 (not K)
Asus Z170-A with Realtek ALC892
2x8G DDR4-2666
Asus GTX 1070 Dual O8G
Windows 10 64bit
(Full list)


I have a pair of speakers with S/PDIF and analogue input. The sound have been working fine from the S/PDIF out of the motherboard. I have set the line-in to listen mode so the S/PDIF stay on.

The PC have been used with two monitors, one connected via DVI and one connected via a HDMI->DVI adapter. Last week I replaced the DVI monitor with a Dell S2716G (1440p G-sync), connected by DisplayPort. Games are running great, but I started noticing random popping sound from the speakers when in games.

The pop sound is correlated to GPU load, just enabling GPU computing task in Folding@Home would cause it continuously. It sounds like the optical signal keep getting switched off and on. Switching to analogue output from the motherboard reduce the pop frequency, but I can still hear a bit of it.

I have tried:
- Update Realtek driver.
- Roll back to older Nvidia driver.
- Disable Nvidia audio output device in device manager.
- Disable "High Definition Audio Controller" on the same PCI bus as the GTX 1070 in device manager.

None of that helped much. Any idea on what else I should try? Is it a system bus bandwidth issue?

Not tried yet:
- Update BIOS. (Already second to newest)
- Flesh install windows.
- Give up and use the headphone out of the monitor as speaker out.
- Return the new monitor and go back to DVI.

 

[UN1Xnut]

Sounds like a case of ye olde analog electrical interference and, possibly, failing hardware. No amount of tinkering around with software will fix this.

Start with the obvious things... Is all the RF shielding installed in the computer case (all metal PCI slot covers, motherboard IO shield, any metal 3.5"/5.25" covers the case may have had, etc)? All the motherboard mounting screws in place? Is all the equipment (computer, monitor, speakers, etc) plugged into the same outlet, preferably the same power strip? Try to unplug and re-seat all internal and external connectors (possible bad grounds)? Are you using a USB connection to the monitor in addition to DP?

 

[rain shadow]

If it isn't already something UN1Xnut mentioned, I would be looking at the DC side of things. A bad VREG, the power supply getting flakey, missing or bad PCIe aux power to the video card, something along those lines. My thinking is that when the GPU gets going it's using more power and putting more stress on the supply and distribution.

 

[redleader]

Since he is using optical out, some kind of actual interference seems really unlikely. I also really doubt it is a power issue if the system is stable. An LED does not use very much power and will be far less sensitive to voltage droop than actual logic. An easy way to rule this out however is to just disconnect the DP monitor and see if the problem goes away. If it does, it is not a hardware problem.

"pop sound" to me sounds more like a digital problem where the FIFO runs dry and inserts bad samples. Does your DPC latency look ok? http://www.thesycon.de/eng/latency_check.shtml

 

[r8dhex]

Not much to contribute here, but when I was using my motherboard audio, I would hear hums, and pops that correlate to my GPU and/or CPU activity. I eventually used a USB soundcard.

Also, this can't be good for your audio

- Flesh install windows.

 

[cf18]

Kind of stuck... DPC latency are low yellow when system is idle or playing game. It go all green only when Folding@Home go 100% on CPU and GPU, but it also when the sound popping at the worst.

Removed the broken DVD drive (SATA plug broken, some time works some time doesn't) , no change.

Unplug the USB3 hub of the new monitor, no change.

Unplug the new monitor using DVI monitor only, no change.

System Restore to a date before the new monitor arrive, no change.

The only other recent hardware change is a fixed speed 120mm exhaust fan was replaced with a regular one plugging into fan header 2. No way that can cause this problem, right?

For now at least the audio out from the monitor works.