What is the ideal specs for a general use 120mm chassis (case) fan?

[Pherdindy]

So I am looking for the ideal specifications for a chassis fan that is robust (I am pretty sure most people would do the plug and play approach rather than really look at the technical specifications).

 

I believe the goal is to maximize the air flow (CFM) while taking into consideration the rated voltage (VDC) to be 12, current requirements (A), revolutions per minute (rpm), noise levels (dBa), reliability of the fan (sleeve, ball, hydraulic bearing), type of connector pin (2-pin, 3-pin, and 4-pin), number of blades, size of the blades, and shape of the blades.

 

I noticed that majority of the people buy cheaper fans that are around 500-1800 rpm only and have a maximum airflow of around 50 CFM and below (more noticeable on budget RGB variations). But I never really see any fans that go above 2000 rpm for chassis use as well as maximum air flows above 75 CFM generally. I believe it's mainly because of the noise levels it will generate? Also, people mostly use hydraulic bearings and I don't really see people selling sleeve/ball bearing types so far (except for 1 in my sample which is a rifle bearing--a sleeve variation). Almost all are also 4-pin connectors (PWM feature that important?) with a few 3-pins while 2-pins are almost non-existent. 

 

Below is a list of fan specifications that I have found, but I don't think I have seen anyone sell chassis fans using these values. On paper I would say it's awesome due to great cooling, but the fact that no one is selling at these specifications makes me wonder why. Values of interest are higher currents and noise levels which are generally twice the usual values of "quiet' fans.

 

 

 

Below is also a list of some fans I have sampled in the market and their technical specifications. Most people are in it for the RGB feature as well:

 

 

 

 

Ideally the current is 0.25A or less due to the limit of the motherboard fan port to be around 1A and most people use some kind of splitter that does not necessarily connect to the SATA port. An example is this one by Deepcool where is connects to one of the fan ports.

 

However, there are fan hubs that support up to 10 independent fans that powers through the SATA port. So given that it can handle higher currents (higher wattage), does that mean I can plug 10 fans that are let's say 0.4A and have no problems?

 

 

So the only things I can think of why getting 3000-4000 rpm is bad is because of higher power/current requirements and twice the noise levels. However, I have chassis fans with around 18 dBa to 35 dBa and I can't really hear anything so i'm not sure if it will be significantly noisy.

 

 

[Mick Naughty]

If you cant hear your fans now, your hearing is worse than mine. Every fan I own is too loud for my liking but nothing I can do about that but run them slow.

If you want a fancy fan for an actual purpose then get it. Just like owning a server, all the noise to help in inefficient build. If the extra airflow is actually gonna do something, go for it.

[bowrilla]

The specs are nothing more than a nice hint. The values are not measured in the same way and relate to different rev ranges and since CFM, static pressure and noise are not linear functions, those specs don't mean much. You'd need normalized values at at least 3 different revs to get an idea. 

 

The theoretically perfect and ideal fan has infinite CFM, infinite static pressure while almost no movement and zero noise. Obviously such a fan does not exist.

 

PWM is more efficient and precise than voltage controlled fans, 2 vs 3 pins means rev signal or not.

 

If you can't hear 30dB of fan noise (per fan) then you should see a doctor, because you seem to need hearing aids. 30dB are about the level of someone whispering. Yes, it's not very loud, but it IS noticeable or you have hearing damage.

 

If you don't care for noise and want raw cooling performance: Noctua Industrial PPC fans can be had with 3000rpm max (120mm fans with 186.7m³/h and 7.63mm H2O at 43.5dB, 140mm whopping 269.3m³/h and 10.52mm H2O at 41.3dB, next step would be full "Blowimatron" industrial fans that can chop vegetables). I really wonder what you intend to do with those though. Realistically you're fine with fans running around 500-900rpm in a properly build system.