Why Your Power Supply Is Buzzing and What to Do
Your computer makes a buzzing, humming, whining, or clicking noise that seems to come from the back or bottom of the case — where the power supply unit (PSU) sits. The noise might be constant, or it might change with the computer's workload (getting louder during gaming or rendering, quieter at idle). Power supply noises range from harmless annoyances to warning signs of impending failure, and identifying the type of noise tells you which category yours falls into.
Coil whine
Coil whine is a high-pitched buzzing, whining, or squealing that changes frequency with the electrical load. It sounds like a faint mosquito or a high-pitched hum that shifts pitch when the computer is doing different things. The pitch often changes when you move the mouse, scroll a web page, or start a game — these activities change the power draw, which changes the frequency of the whine.
Coil whine is caused by vibration of the wire coils in the PSU's inductors and transformers. When alternating current passes through a tightly wound coil, the magnetic force can physically vibrate the wire wrappings against each other. The vibration frequency is in the audible range (typically 1 to 10 kHz), producing the characteristic whine.
Key facts about coil whine:
- It is not dangerous: Coil whine does not indicate a failing or defective PSU. The power supply functions correctly — the noise is a mechanical side effect of normal electrical operation
- It varies between units: Two identical PSU models can have different coil whine levels because the manufacturing tolerance of inductor coils varies. One unit might be silent while another of the same model whines audibly
- It can come from the GPU too: GPU coil whine sounds identical and is actually more common than PSU coil whine. To determine the source, bring your ear close to the PSU (rear/bottom of case) versus the GPU (middle of case) while the noise is happening. The location is usually obvious from close range
- Load-dependent: Coil whine typically gets louder during high-power operations (gaming, rendering, stress tests) because higher current through the coils produces stronger magnetic vibration. If the buzzing only happens during heavy use and goes away at idle, coil whine is the most likely cause
- Fixes are limited: You cannot eliminate coil whine from a specific unit without replacing the inductors (not practical). Undervolting the GPU (reducing its voltage to lower power draw) can reduce GPU coil whine. Capping frame rates in games (using V-Sync, a frame rate limiter, or RTSS) reduces the rapid power fluctuations that excite coil whine. If the PSU coil whine is unbearable, replacing the PSU with a different model (or even a different unit of the same model) is the only reliable solution
Fan bearing noise
The PSU fan keeps the internal components cool. Like any fan, its bearings wear out over time, producing noise that gets worse as the bearing degrades:
- Humming or droning: A low-frequency hum that is constant regardless of computer load. This is the sound of a bearing that has worn its lubrication but is still spinning smoothly. It is louder than a healthy fan but not yet grinding
- Grinding or rattling: A rough, irregular noise that sounds like something rubbing or scraping. This indicates the bearing is physically deteriorating — the ball bearings (in a ball-bearing fan) are damaged, or the sleeve (in a sleeve-bearing fan) has worn to the point where the shaft wobbles. Grinding means the fan is close to failure
- Clicking or ticking: A rhythmic click once per fan revolution. This can be a wire or label touching the fan blades, or a bearing with a specific defect that produces a click at one point in its rotation. Open the case and visually check if anything is contacting the fan blades. If not, the bearing itself is clicking
- Intermittent noise on startup: The fan makes noise for the first few minutes after power-on, then quiets down. This is common with sleeve-bearing fans — the lubricant redistributes after sitting idle overnight, and the bearing is noisiest before the lubricant warms up and spreads. This is an early sign of bearing wear
Fan bearing noise is a maintenance issue. The PSU itself is working correctly, but the cooling fan needs attention. However, PSU fans are not easily user-replaceable because opening a power supply exposes dangerous high-voltage capacitors that can hold lethal charge even when unplugged. Replacing a PSU fan requires discharging these capacitors safely — this is not a routine DIY repair. If the fan noise is severe, replacing the entire PSU is the safer option.
Electrical buzzing or humming
A steady 60 Hz hum (the frequency of US wall power) can come from the PSU's transformer. This is different from coil whine — it does not change with computer load, and it sounds more like a transformer hum (similar to the sound a large wall adapter or fluorescent light ballast makes). A transformer hum that is new (the PSU did not make this noise when it was newer) can indicate loosening of the transformer windings, which happens as the varnish holding the windings in place ages and cracks.
A transformer hum is not immediately dangerous, but it does indicate aging of the PSU's internal components. If the hum is accompanied by other symptoms (voltage instability, random restarts, burning smell), the PSU should be replaced promptly.
Warning signs that require replacement
Some PSU noises indicate actual problems that need immediate attention:
- Crackling or arcing: A sharp crackling, snapping, or popping sound from inside the PSU is a serious warning. This can indicate arcing between components — electrical discharge jumping across a gap due to insulation breakdown. This is a fire risk. Turn off the computer immediately and do not use it until the PSU is replaced
- Buzzing accompanied by burning smell: A buzzing or humming combined with a hot, acrid, or chemical smell means a component inside the PSU is overheating or has failed. Capacitor failure often produces a distinct sweet or chemical odor. Shut down immediately
- Buzzing with visible smoke or discoloration: Any visible smoke from the PSU or discoloration of the PSU casing near the exhaust indicates an internal fire or component destruction. Shut down, unplug, and replace the PSU before using the computer again
- Noise accompanied by system instability: If the buzzing or humming coincides with random restarts, blue screens, or the computer failing to start, the PSU may be failing to deliver stable power. The noise from a failing capacitor or transformer is the sound of a component that is no longer functioning within its design parameters
Diagnosing the source
Before replacing the PSU, confirm that the noise is actually coming from it and not from another component:
- Listen closely: With the case open and the system running, carefully bring your ear close to each component — the PSU, the GPU, the CPU cooler, case fans, and hard drives. Mechanical hard drives make clicking and humming noises that can be confused with PSU noise. GPU coil whine is often blamed on the PSU because it is similarly high-pitched
- Use a straw or paper tube: Roll a piece of paper into a tube and hold one end to your ear while pointing the other end at different components. This acts like a stethoscope and helps isolate the source of the noise
- Disconnect components: If you suspect a specific fan, temporarily disconnect it (one at a time, with the system off between changes) and check if the noise stops. Do not open or disconnect the PSU itself — only disconnect fans and drives that have accessible power connectors
PSU noise diagnosis in Columbus
Luxurious Computers diagnoses power supply noise — identifying whether the sound is harmless coil whine, a worn fan bearing, or a warning sign of component failure, and replacing the PSU when needed with a properly rated replacement.