Mack and Hookem, I agree that their could be "unusual" instances. But answer me a question. Why do you prefer the panaflow LO? Which model is that exactly?
FBA08A12L
24 CFM at 21 dBA, 12VDC
In my personal experience, the Panaflo LO is indeed quieter than the Vantec stealth fan, despite the rated specs. I have indeed used several of both types, so I can draw that comparison. This is due in part to variable measurement techniques, a lack of accountability for those measurements, and the fact that the Panaflo's have fluid bearing that is much quieter (at least to my ears and those of other seasoned system builders) in actual operation than the ball bearing fans of similar rated noise levels.
With proper placement of 2-3 of these Panaflo's for case cooling, I have never needed a greater CFM rated-fan in most cases. Given my cooling needs, their reputation for quality, and my good past and present experiences with them as quiet fans, they remain my case fan of choice in most instances.
In my opinion, if a fan is going to be running at its lowest setting all time, then it's the wrong fan for the application. Furthermore, many fans can begin to "growl" or make other irritating, regular noises after being run at low speed for long periods of time. (Not always, but certainly often enough to bear in mind when selecting a fan.)
Before we proceed to directly compare fans and CFM / dBA ratios (which I generally feel is a good idea, but have since come to value less), let's discuss a few other issues.
First off, any electrical component will vary from its spec. For many components, this variation is on the order of 5-10%. Furthermore, fan speed varies linearly with voltage, and most PSU 12V rails aren't putting out exactly 12V. (At the moment, I'm reading 12.60V on mine, for example.) These two effects will compound with one another to potentially give a sizeable difference in CFM from spec. Let us say 5% to be conservative.
The noise measurement of the dBAs tends to be a bit spottier and doesn't take restricted airflow, transmission of vibration, resonance, etc., into account. Let us be generous and allow a mere 5% variability to that as well.
So, let's find a range of variation: An acutal application could yield CFM / dBA as low as .95 * rating / 1.05 * rating = 90.4% of its rating, or as high as 1.05 * rating / .95 * rating = 110.5% of its rating. Now, let's keep this in mind as we compare an example:
Panflo LO:
24 CFM / 21 dBA = 1.1 (Bear in mind we only had 2 significant digits in our ratings, so we couldn't possibly have more than 2 accurate digits in our ratio.) By our calculation above, the actual figure could be anywhere in [.99,1.2]
SF II at low speed:
25.2 CFM / 19.95 dBA = 1.26,
which could be anywhere in the range [1.13,1.39]
Now, the winner isn't quite so clear-cut. There is some overlap in what a user may experience (.07 overlap, which just under half their rated difference), and in some cases, the SFII will give greater airflow / noise, and in other cases, the Panaflo. Once again, I believe we have been overly generous in treating the variability and accuracy of the dBA ratings. If you allow for a 10% variation, the ranges increase to [.95,1.3] for the Panaflo LO and [1.09,1.47] for the SF II on its lowest setting. That gives an overlap of .21 whereas their ratings only differed by .16.
In other words, these CFM / dBA ratings are extremely sensitive to measurement error and variability, and so they should be taken with a grain of (kosher-sized) salt.
Furthermore, the A-weighted decibel was devised to approximate the human's response to sound at different frequencies, but it is not a precise figure set in stone. It varies by the individual. Many here have expressed that despite the A-weighting, they would prefer a higher-dBA-rated larger fan (with a lower frequency for the peak noise level) than a lower-dBA, smaller fan (with a higher-frequency of peak noise level.) Also note that the dBA only measures peak noise level. However, repeated noise patterns (such as bearing sounds), even at sub-peak noise levels, can be just as irritating or perceived to be just as loud, if not louder. In the middle of the night, is the sink dripping on the other side of the house really all that loud? Human perception is a marvelously strange, marevelously complex thing, and it is difficult to express that in a single number. "Quiet" is in the ear of the beholder. Even if you completely believe the dBA figures, one user may perceive a louder fluid bearing to be quieter than a ball bearing fan with a lower noise rating due to these types of factors.
I looked up all the 80mm Panaflo fans and the Tt Smartfan can match or beat everyone of them at the db level.
Panasonic Panaflo Axial Fan 80x80x25.5mm, Ball Bearing, DC 24V, 1.68W, 3200 RPM, 14.1 CFM, 24.0 dB-A Model: FBA08A 24L1A
The Tt SF II does 20.55CFM @ 17db Winner
Panasonic Panaflo Axial Fan 80x80x25.5mm, Ball Bearing, DC 12V, 2.08W, 2950 RPM, 39.6 CFM, 32.0 dB-A Model: FBA08A12H
The Tt SF II 32db will be at approx 45CFM Winner
I'm not going to comment on all of your comparisons, but I would like to point out that the decibel is a logarithmic scale, and as such, it is probably inaccurate to linearly interpolate it. (I can't find where you got that data on Thermaltake's site, so I'll assume you either guessed it to be midrange or back-calculated and interpolated / estimated it.) If you have other sources or methodology, please feel free to state them.
Panasonic Panaflo Axial Fan 80x80x25.5mm, Ball Bearing, DC 12V, 3.24W, 3450 RPM, 46.9 CFM, 38.2 dB-A Model: FBA08A12U
The Tt at 38db will be at approx 54CFM winner
Is there another Panaflo your talking about??
I don't see how any of these panaflos compare to the SFII. It beats them hands down and still allows the flexibility to run it at higher or lower speeds.
In real-life applications, it still beats them, depending upon the use and the settings, but not so definitively given measurement and other variability. Given a large enough variability, they may not beat them at all.
Now lets move into your numbered things.
1). Yes cost would be the only reason. But for $4extra you get the total flexibility of the SFII over a panaflo or such.
But if that is a feature that isn't desired, it's unnecessary overhead. A penny saved is a penny earned. How about 400 of those? If I really don't want French fries, I'll just order the sandwich and drink if it saves me 15 cents. You'd be amazed at how quickly that mindset can add up!
2). Yes but I did specify 80mm fans. Why would you not want more airflow at less noise???????
I'll agree on the 80mm point. My apologies for straying off topic. You're discussing the existence and choice of the optimal 80mm fan choice for almost all users in almost every application.
We all want more airflow at less noise. My point is that this is not the only factor that needs to be considered, and to some extent, one cannot precisely compare all these choice based on the on-paper ratings alone.
Furthermore, while everybody wants more cooling / noise, most everybody also has a threshold max noise level. A (hypothetical) fan that does 100 CFM at 50 dBA wins your CFM / dBA comparison, but if a users's threshold tolerance is 35 dBA, it's an unacceptable choice. This is not just an optimization problem: it's an optimization problem with constraints.
3). Again, You must not read my post completely. The SF comes with it's own fan adjustment so the noise is purely what ever you want. The Tornado was only the choise if you didn't care about noise.
My apologies. The last time I checked, these fans could be controlled thermally (which means you don't get a choice), full speed, or LO/MED/HI static speeds. I didn't realize that they have a completely variable setting now. Perhaps I confused it with the original SF.
However, regarding the temp control, I like the concept of a fan with built-in temp control, but I don't like the fact that they choose the temperature response function. I also believe that depending upon the application, the user will want to select what the range of CFMs, dBAs, and RPMs for the fan are over the temperature range.
4). Lets be serious. How hard is to turn a dial?
We're talking about most users. That's a mighty broad category. Would my parents really enjoy turning the dial to one setting when running CPU-intensive tasks, and another for email, etc.? Certainly not. Not everybody is going to want to bother with what SHOULD be a routine task that isn't even thought about: keeping the computer cool enough to ensure stability and protection of the components. There are plenty of computer users out there who wouldn't want to watch CPU temps and adjust the fan speeds accordingly (or more generally, according to use), just as I don't particularly relish the thought of tweaking my car's cooling and fuel injector system properties according to the type of driving I anticipate. A fanbus isn't for everybody. (Granted, that's where either a temp-controlled fan or a static-speed fan comes into play. Either way, it has to be well-selected for the application.)
4b) see 4
Why install a variable-speed fan to run it at low or nearly-low speed all the time, when you can simply get a fan that does what you want it to do in the first place? Also, a variable-speed, temp-controlled fan is only useful if it operates within the desired noise levels all the time.
From the specs, I don't think the SFII is a good choice for a temp-controlled case fan. It is not uncommon to find room temps in the 24-27C (75-80F), and at these temps, the SF won't be operating at its 17 dBA setting, rather just on the low side of its medium setting. So, the SFII may not be a good choice for a quiet temp-controlled case fan except in a well air-conditioned house or apartment, for example.
5). Ok but the SFII does come with a light mod if you want it...
Agreed, but again, not a big deal to me.
Now, let me say at this point that I believe that the SFII is a generally good design, and it's one that I have recommended to others when I felt it matched their needs.
The point is that simply winning CFM / dBA on paper is not the only factor in choosing a fan. You were on the right track when you originally stated "except for price" ... Perhaps I should add another numbered point:
6) Desired quality and experience with a particular company's quality.
Past experience with a particular brand may be enough to steer a user away from that manufacturer in the future, and that is completely legitimate.
So I'm back to where have you put up a valid arguement>>
Let's try to keep this civil. Do keep in mind that with such grandiose statements as "Let's put the 80mm fan arguement [sic] to rest" and "Other than pure cost reasons IMO there is [sic] no other fans to buy under most circumstances," you are inviting criticism. I have tried to be polite in my response, and as such, I've spent a good time rereading this response prior to posting it.
-- Paul
