Editing Quiet PC (section)

===Power supply===
{{Main|Power supply unit (computer)}}
[[Power supply]] (PSU) is made quieter through the use of higher efficiency (which reduces waste heat and need for airflow), quieter fans, more intelligent fan controllers (ones for which the correlation between temperature and fan speed is more complex than linear), more effective heat sinks, and designs that allow air to flow through with less resistance. For a given power supply size, more efficient supplies such as those certified [[80 plus]] generate less heat.

A power supply of appropriate wattage for the computer is important for high efficiency and minimizing heat. Power supplies are typically less efficient when lightly or heavily loaded. High-wattage power supplies will typically be less efficient when lightly loaded, for instance when the computer is idle or sleeping. Most desktop computers spend most of their time lightly loaded.<ref name=SPCRPower>{{cite web| url = http://www.silentpcreview.com/article699-page1.html | title=Recommended Power Supplies| first= Michael ‘Mike’ | last = Chin| date=2006-12-01 |publisher=SPCR |access-date=2008-10-10}}</ref> For example, most desktop PCs draw less than 250 watts at full load, and 200 watts or less is more typical.<ref>{{cite web| url = http://www.silentpcreview.com/article28-page4.html |title= Power Supply Fundamentals| first = Michael ‘Mike’ | last = Chin|date=2005-04-06 |publisher=SPCR |access-date= 2008-10-10}}</ref>

Power supplies with thermally controlled fans can be made quieter by providing a cooler and/or less obstructed source of air, and fanless power supplies are available, either with large passive heat sinks or relying on convection or case airflow to dissipate heat. It is also possible to use fanless DC-to-DC power supplies that operate like those in laptops, using an external power brick to supply DC power, which is then converted to appropriate voltages and regulated for use by the computer.<ref>{{cite web| url=http://www.silentpcreview.com/article601-page1.html|title=Tiny, Silent and Efficient: The picoPSU | first = Michael ‘Mike’ | last = Chin| date=2006-05-09 |publisher=SPCR |access-date= 2023-07-31 | archive-date= 2016-11-19 | archive-url = https://web.archive.org/web/20161119011614/http://www.silentpcreview.com/article601-page1.html | url-status = dead}}</ref> These power supplies usually have lower wattage ratings.

The electrical coils in power supplies can produce [[Electromagnetically induced acoustic noise and vibration|audible electromagnetic noise]] which can become noticeable in a quiet PC.

Equipping the PSU with a power cord that uses a ferrite bead can sometimes help to reduce humming from the PSU.