Window shopping for fans

A project log for Warm side cool, cool side warm

A speculative DIY register booster project to even out the temps around my home.

WJCarpenterWJCarpenter 08/14/2022 at 21:280 Comments

I spent a little time comparing PC cooling fans, based on the time-honored tradition of googling and looking at resulting lists of "best" fans, plus a couple of sites that specialize in quieter PCs and either sell or recommend fans. I only looked at PWM fans in the 92mm and 100mm sizes. Actually, I didn't find any 100mm fans with PWM. The only candidate that I found was SilenX, and they say that PWM fans are a bad idea for noise control. So, my list is all 92mm fans. 92mm fans are less common than 80mm and 120mm fans, so there is less variety to look at.

CFM and static pressure have an inverse relationship, though it's not strictly linear. It's understood that the CFM figures quoted are maximums, as are the static pressure figures. Some manufacturers provide noise levels at minimum and maximum RPMs, but most provide only a single figure without stating an RPM value. Until I find out otherwise, I'm assuming they quote a figure that makes them look the best, which would be the minimum RPM. One interesting counter-example is the be quiet! fan, where they give a noise figure for the maximum RPMs. 

Another interesting note is that most of the Noctua fans advertise that they turn the fan off if the PWM duty cycle is 0%. I was thinking of using a separate transistor to turn the power to the fans off. Exploiting that Noctua feature would simplify the circuit a little bit, but at the expense of flexibility in fan choices, so I probably will continue with my original plan.

Here's my list. If I find more later, I'll edit the table to add them. The fans marked with an asterisk were tested for noise (results in a later project log).

ModelNoise dbRPMs CFMstatic pressure (mm H2O)
*Arctic F9 PWM PST???-14.8150-1800431.35
Nexus PWM Silent15.8-27.8700-250043.53.15
Noctua NF-A9 PWM22.8400-200046.42.28
Noctua NF-A9x14 PWM19.9500-220029.71.64
Noctua NF-B9 redux-1600 PWM17.6350-160037.81.61
Noctua NF-A9 PWM
Noctua NF-A9x14 HS-PWM
*Gelid Silent 9 PWM11-23.5900-200037.92
*be quiet! PURE WINGS 2 PWM???-19.6500-190033.21.65
CoolerMaster Blade Master17-35800-280054.84.27
*CoolerMaster Sickleflow6-25650-2300401.8