The charts on this page compare various fans that run slowly and make little noise. Even though they may not cool down an overclocked system they may be just what you want for case fans.

Some of these fans are connected to Voltage reducing adapters. The brand sellers include these so you will not need a fan controller. In addition to their monetary cost, fan controllers usually cost you a 5.25-inch slot, and may cost you some noise, as some fan controllers can make a fan noisy. The Noctua is on a resistor, and the Deepcool fans are on an adapter that bridges the 12v and 5v lines of your PSU to produce a net 7 Volts. The Coolink SWiF2 120P is run a 0% PWM duty to emulate a SWiF2 1200, which is designed to run at 800 RPM. The Thermalright TY-140 is run at 0% PWM because it is an important fan, and you may wish to know how it sounds at idle.

Use the first chart to look up a specific fan. Use the second to compare fan noise (approximated by Sound Pressure Level, or SPL) for fans of similar cooling power. And use the third chart to compare the cooling power of fans with similar SPL's. Note that due to the limitations of the test system, fan SPL below 12-14 dBA cannot be assessed. Some of these fans almost certainly run more quietly than their measurements.







Some of the fans were also measured on the overclocked setup. In this way you can mentally compare the less powerful fans with those in the overclocked comparisons.
Fan Performance on a non-overclocked system