Editing Computer fan control (section)

==== Voltage modification ("volt modding") ====
The voltage a computer cooling fan receives is defined by the difference between the voltage wire (+12&nbsp;V) and the ground wire (+0&nbsp;V). By connecting one or both wires to a different voltage, the voltage the fan receives will be different from the default 12&nbsp;V the fan was designed for.

Increasing the voltage<ref>{{Cite web |url=http://afrotechmods.com/fanmod.htm |title=Overspin Your Fans |access-date=2017-04-05 |archive-date=2002-06-09 |archive-url=http://web.archive.bibalex.org/web/20020609204344/http://afrotechmods.com/fanmod.htm |url-status=dead }}</ref> over the default 12&nbsp;V can be achieved by e.g. connecting the −12&nbsp;V or −5&nbsp;V power line instead of the ground wire in the fan connector, and by connecting the 5&nbsp;V power line in the +12&nbsp;V input of the fan connector. Through this procedure, 10, 17 and 24&nbsp;V voltages can be achieved, with voltages exceeding 12&nbsp;V being potentially damaging to the computer fans rated at 12&nbsp;V. However, the combination of modern power supplies no longer being required to provide a −5&nbsp;V power line and the limited power delivery capability of the −12&nbsp;V line (usually less than 1&nbsp;A of current) reduces the total capacity for volt modded fans in modern systems.

Connecting the +5&nbsp;V power line to the +12&nbsp;V input of the fan reduces the voltage the fan receives to +5&nbsp;V. Some fans will not work at such low voltage at all, while some other fans may run at +5&nbsp;V once they have started rotating at a reasonable speed.{{citation needed|date=March 2021}}

Another method of reducing the fan speed<ref>{{Cite web |url=http://www.silentpcreview.com/article6-page1.html |title=Get 12V, 7V or 5V for your Fans |access-date=2016-09-03 |archive-date=2008-09-18 |archive-url=https://web.archive.org/web/20080918053545/http://www.silentpcreview.com/article6-page1.html |url-status=dead }}</ref> is by moving the 5&nbsp;V wire in the classical [[Molex connector|Molex power connector]] in the place of the Ground wire going to the fan, thereby delivering +7&nbsp;V (12&nbsp;V − 5&nbsp;V = 7&nbsp;V) to the fan. However, this is a potentially risky method, because +5&nbsp;V PSU line is intended to source current only, not sink it, so the PSU is likely to get damaged in case of load on 5&nbsp;V PSU line being below the load generated by 7&nbsp;V fans (e.g. when PC enters idle/sleep state). Also, the components inside the computer using +5&nbsp;V power might be exposed to over 5&nbsp;V in case of a short circuit in the fan.