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How do silent PC power supplies work?

If you're a gamer, the last thing you want is to struggle to hear your game over your power supply. Can this be reduced? Learn how a silent PC power supply works.

A tower PC with the side removed to show the components, including the power supply and cabling.


Systems engineers might call the power supply the PS, the P/S, or the PSU. This last term abbreviates “power supply unit.” No matter what you call it, it's not the most intriguing part of a PC system.

So, many computer builders ignore it. Pros and hobbyists both make the mistake of under-investing in this component.

Yet, this mistake comes with a frustrating price: noise.

A sub-par PSU can be loud. Sometimes, it's loud enough to distract you from your game. And, the sound can indicate a more dangerous problem.

So, what can you do? First, learn what a PSU is and how it works.

Then, create--or purchase--a virtually silent PC power supply. Troubleshoot noise problems, discover existing solutions, and determine the best quiet PSU for your system.

Ready? Let's go.

What is a PC's Power Supply Unit?

Contemporary homes and buildings are connected to the power grid. The power grid is an Alternating Current (AC) electric power supply.

Alternating electric currents regularly reverse direction. Their movements form a wave. Radio waves - including the high-frequency bands that carry Wi-Fi signals - are AC waveforms.

The power grid delivers electricity to buildings. Then, appliances plug into outlets in building walls. Thus, the device utilises the power grid's electricity to function.

It costs less to generate AC power than we'd spend on alternatives. But, not all devices can use AC power. Many electronic devices utilize DC circuits.

DC vs. AC

DC circuits utilise electric currents that only flow in one direction. Engineers call currents that maintain a single direction, without reversing, direct currents. DC circuits direct the predictably linear DC flow into useful configurations.

Eventually, a PC, a smartphone battery charger, or an electric bike needs to connect to the grid. So, we use a Power Supply Unit. PSUs convert AC power to DC power.

How do PSUs work?

Your PC runs on DC power. All internal PSU parts work to take AC power and flip it into DC. When this process risks overheating, the PSU's fan cools it down.

To understand how a PSU works, explore its metal-cased exterior. Then, examine how its internal parts bring power from the grid to your computer.

PSU exterior

The front of the PSU's exterior is cables. These connect to the PC's hard drive, the motherboard, and other computer parts. The back of the PSU has:

  • A connection for the power cord
  • An exhaust vent that lets the fan push out hot air
  • A rocker switch, which lets you turn the power supply on and off
  • A red switch, which lets you adjust the PS voltage

It's not a good idea to open a PSU box. Only interact with exterior parts.

Interior parts can deliver a severe electric shock, even if it's been unplugged for a while. After all, a PSU has several highly-charged capacitors ready to go.

AC-to-DC conversion

As AC electricity enters a PSU, it runs through transient filters. Transient filters use capacitors to refine AC power. In this case, refining means blocking abrupt voltage spikes.

1. Filters to Transformer

A complex PSU might have many filtering stages. Then, a transformer receives the filtered AC power. It modulates the voltage, stepping it up or down.

2. Transformer to Rectifier

The transformer sends the power to the rectifier. The rectifier changes the AC power to DC. It may be a single diode or a complex circuit.

The best rectifier outputs the same amount of DC power (in volts) as it received in AC power. But, lower-quality rectifiers lose some power as heat energy.

3. Post-Rectifier options

After the rectifier converts the current, PSUs vary. In some, the rectifier sends the DC power to another filter. In others, it directs the power to a power factor correction converter.

These components both ensure the PSU delivers the correct amount of power. They just reach that end by different means.

Either component might integrate a heatsink. And, both components serve the power to the voltage regulator.

4. Voltage Regulator to PC

A voltage regulator makes sure the PSU's DC voltage output is steady and consistent. It maintains consistency regardless of the input. There are three voltage regulator styles:

  • Series
  • Shunt
  • Integrated Circuit (IC)

The voltage regulator sends power to the cables.

Ratings and rankings

Developers rate PSUs by their DC output. They measure this output in watts (W). This tells you how many DC watts the PSU delivers hourly.

The average gaming PC uses 1400kWh of electric power annually. Think about how often your PC will be on.

Then, you can use a conversion calculator to learn what DC output you'll need. Most gaming PCs work well with 500W - 650W PSUs.

Six reasons for PSU noise

Now you know how a power supply works. What makes them so loud? If you want a silent PSU, learn why they make noise in the first place.

1. PSU fan disruption

A loud, harsh noise might mean the fan blades are hitting something. If a wire is poking the fan through the grille, the sound will be loud.

Fortunately, it's easy to clear wires and debris away from the fan - unless, of course, the fan blades are smacking a solid object stuck behind the grille. In that case, get professional assistance.

2. Worn, warped, or broken fan

Frequently, the source of loud PSU noise is the fan. Worn out, warped, and broken fans make erratic sounds. Or, they whirr at odd frequencies.

High-quality PSUs use top-tier materials. If you replace the fan, seek out something resilient.

3. Overworked fan (inefficient AC-to-DC conversion)

An overworked fan sounds stressed. It's also on too often.

A PSU's fan boots up to cool the interior. But, ideally, the rectifier won't generate that much extra heat often.

If it does, something's off. Your PSU's process isn't efficient.

You might need to replace parts. Or, you might need to make sure your PSU is rated for the amount of power your PC uses.

Alternately, your AC input may be unusually erratic. In this case, a surge protector can help significantly.

4. Loose screws

A loud rattling sound can indicate loose screws. The PSU's case is screwed together. Check if you need to tighten any of them.

5. Clogged intake or exhaust

A power supply typically takes in room-temperature air. Its fan pushes heated air out of the exhaust. The fan works overtime if either passage is blocked.

An air intake is at the bottom of the PSU's case. Elevate the case a bit if the carpet blocks the opening. Also, if there's a mesh dust filter over the intake, clean it.

The exhaust vents out the back of the PSU case. Make sure the opening isn't blocked by a wall or the PC case. The air needs room to flow out.

6. Power-conditioning coil vibration

A harsh electric buzz might be an over-active coil. Coils within PSU parts might vibrate when power is high.

The AC frequency may match components' natural resonant frequency. Or, components' resonant frequencies may match one another. This makes both vibrations increase.To avoid this, look for devices that use sound-absorbing coatings.

Is a silent PC power supply possible?

True silence might only be possible with soundproofing. That said, most users just want a reasonably quiet PS. Full silence isn't a necessity.

Fortunately, engineers have tackled the PSU noise problem from many angles. Consider these four quiet PS options.

Best quiet PC power supply options

Designers categorize quiet PS devices as “passive” or “active”. Active PSUs address overheating with a fan. Passive devices use other methods.

1. Fanless PSU with heatsink (passive)

Most popular silent PSUs use a heatsink instead of a fan. A heatsink can be made of a thermo-conductive material. This lets it absorb and dissipate excess heat the process generates.

Other designers create heat sinks designed to induce convection. Convection currents naturally excise excess heat.

Some silent modular PSU creators claim their devices never need cooling. Their PSU's AC-to-DC process is maximally efficient. It never generates excess heat.

This claim is hard to test. Notably, only low-watt PSUs boast no fan and no alternative.

2. Fanless PSU with liquid cooling (passive)

Some silent PSU developers swapped out the fan with new technology. A liquid cooling power supply disperses excess heat with fluid.

Engineers cool servers with liquid solution immersion. Liquid cooled PSUs take a similar strategy on a much smaller scale.

That said, some critics raise concerns about leaks. A coolant leak could damage your PC.

3. Advanced fan technology PSU (active)

Some active PSUs are surprisingly quiet. Larger PS devices allow for strategic fan placement.

And, engineers have made sturdier, non-warping fans - thanks to advances in materials science.On top of these developments, PSUs got smart. Intelligent PSUs respond better to heat and voltage fluctuations.

Every component is programmed to predict and react to changes. As such, these PSUs rarely call the fan into action.

4. Quiet mode PSU (semi passive)

A semi-passive PSU uses a bit of everything. It may include other cooling options in addition to a fan. And, some semi-passive PSUs react intelligently to changes.

The best of these devices give you choices. One choice might be quiet mode.

This lets you switch to a fanless, low-power mode when you want it. Then, you can switch back to full power later.

The Best PSUs For Your PC

There are silent PC power supply options. But, there's no single, best silent power supply.

At CCL, we know each use case is different. That's why we regularly publish guides, articles and other useful information to keep you informed.

Explore our huge range of PSUs now.