[SOLVED] LED room lights flicker when PC is idle

[trail_posture]

I put together a new build recently, and for some reason, now the ceiling lights in the room flicker consistently when the PC is NOT under load. The below are my core components:

CPU: Intel 13700K
GPU: MSI 4090 Suprim
Mobo: ASUS Z790 ROG STRIX
PSU: MSI MEG Ai1300P

No crazy extenders or aftermarket cables; basically all stock.

The issue started as soon as Windows setup booted off a boot disk (even before the install started). The lights in the room will flicker almost constantly when the computer is sitting at desktop with no programs running or when it turns the screen off (not hibernation, just display turned off after 5min). The flickering will instantly stop when I wake the screen. If flickering at desktop, just running a YouTube video or something similar is enough to make the flickering stop. Absolutely zero issue when under load/gaming.

At first I thought the wattage was too high for the circuit in the room, so I plugged the computer into one of those power analyzers that plug into the wall. MSI also has software that reports how much the PSU is pulling. Both the software and the power analyzer agreed I'm pulling like 100 - 200 watts under normal use (yes I'm aware the PSU is total overkill, I just really wanted ATX 3.0 and that is what was available). Under load I haven't gone over about 400w, so doesn't seem like I'm drawing too much power out of the wall. Even if that was the case, I'm having issues when the PC isn't under load, and no problems when it is.

Anyone experience anything like this?

 

[Aeacus]

Most likely culprit is EMI.
Further reading: https://www.techtarget.com/searchmobilecomputing/definition/electromagnetic-interference

 

[trail_posture]

Thanks for the response. Any idea how I might test to figure out if this is the case?
Also, any idea why the issue would get better when the PC is under load? This is the piece that is really stumping me.

 

[Aeacus]

Any idea how I might test to figure out if this is the case?

You need EMI detector for that.

Either build it your own (if you're good with tinkering), link: https://www.instructables.com/Electro-Magnetic-Interference-EMI-Detector/
Or buy one, link: https://emfacademy.com/best-emf-meters-and-detectors/

Also, any idea why the issue would get better when the PC is under load? This is the piece that is really stumping me.

Most likely a reduction in the source (in PC) when you put load on PC.

Though, while your PC may be the source, the real issue is with your LED lights controller box. Since this isn't shielded against EMI properly, hence why it "acts up".

The best way to prevent EMI is to use good quality electronics from reputable suppliers. Poorly made, cheap or counterfeit electronics may not be properly tested or may not be EM shielded, making them more likely to cause EMI in other devices and more susceptible to EMI themselves. Modern error correction and filters can also reduce the effect of nearby EMI sources.

In highly sensitive situations, a Faraday cage may be used to shield a device or room from outside EMI.

With this, you could either construct small Faraday cage around your LED lights controller, to shield it from EMI.
Or buy new, good quality LED controller, which isn't susceptible to EMI.

 

[trail_posture]

Appreciate it, I will give this a shot.