Power supply is making noise even when turned off—want some guidance?
Power supply is making noise even when turned off—want some guidance?
Hi, I shared a story about my RM750x experiencing unusual coilwhine. Most people said it was normal, but I’ve noticed it sometimes buzzes quietly even when the switch is off. I’ve asked others before, and responses were mixed—some thought it might be a bad PSU or wiring issues, while others suggested certain capacitors could be the cause. After moving houses recently, I waited to see if it would improve. For a while, I thought it was still happening, but this morning it did again. I tried changing outlets, using a surge protector, and nothing helped. My main worry isn’t the sound itself; I just want to make sure it doesn’t cause future problems with other parts. The noise hasn’t affected my experience for about five months now.
First, check if the noise occurs without the power cord connected. Determine the sound frequency—60 Hz or 120 Hz for AC lines, or different values from converters or interference. You can use a sound generator to listen. If you turn off the switch on the PSU, does the noise cease? Is there an audio cable near the power wires? It might connect to speakers, an amplifier, or your monitor. In Windows, is the audio input active? Are there any microphones connected? Sometimes AC interference affects audio and speakers, making it hard to tell unless something serious happens. Unless there’s a major failure, the PSU likely protects the parts first. I’d suggest waiting a bit longer before troubleshooting.
It’s hard to put into words except for a subtle humming or buzzing that isn’t very loud. This only occurs when the device isn’t powered, but sometimes even when the back switch is off. The sound seems to come from inside the power supply unit. It’s so faint I have to place my ear directly on it.
The faint humming you notice when switching off the PSU is often just leftover charge from capacitors or initial current flow—typically not a warning sign of trouble. Coil whine and minor capacitor noise are normal even in well-made models like the RMx series. If voltages remain steady under load and you don’t experience crashes, restarts, or unusual heat, the power supply is probably fine. This kind of noise doesn’t harm other parts. In rare cases, if it does fail, modern PSUs include safeguards (OVP/UVP/OPP) that safely cut power without damaging your whole system. If it bothers you or gets worse, an RMA might be worth looking into, though scratched connectors usually don’t affect the warranty unless they’re bent or broken.
I believe you're correct. However, your approach of discharging capacitors by keeping the power button pressed while the device is off, then waiting briefly, hasn't resolved the issue. It seems the problem might persist regardless of these steps.
Yes, it's possible. Certain power units may keep emitting a slight hum even after complete capacitor discharge; this is more related to specific component vibrations than residual energy. As long as voltages stay consistent under load and there are no unexpected shutdowns or overheating, it's typically not a reliability concern. If the noise intensifies or alters in nature, it suggests a more serious component issue.
This pattern seems typical. Coil whine or buzzing tends to become clearer when power demand rises and remains steady when the system is off, indicating it's likely just resonance. If voltages stay consistent and you don’t notice overheating or shutdowns, the power supply unit should be functioning well. A slight increase in noise when active but otherwise stable usually points to a minor issue rather than a serious fault.