bit-tech.net

What's the best supersize case fan?

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Dave Lister 9th October 2009, 11:45 Quote
I had to get the antec big boy to replace the fan on my cosmos s and apart from using a molex connector (the original 200mm fan used a little 3 pin connector so the motherboard could control fan speed) this has been a good replacement fan.
SchizoFrog 9th October 2009, 13:08 Quote
On page three... the picture discription states both fans to be on the left...

This is an intersting article and the data revealed quite surprising. That such large fans move little more than standard 120mm fans and quiet noise levels. I'm quite glad that when I modded my side panel (blue perspex) I used a standard Sharkoon blowing directly over my GPU cooler, which resulted in a 10c drop in my GPU temps while being virtually discreet.
IccleD 9th October 2009, 13:41 Quote
I would love to have seen you include one of these in your review...
Performance PCs Monster 360mm Fan.
That fan is surely for those PC modders that have small... overclocks!

Very informative review yet again. I may have missed it though, but what size was your sack? Just wondering if the bigger sacks, which would take longer to fill, would be more accurate than a smaller one?
frojoe 9th October 2009, 13:44 Quote
So basically there are no good large case fans? That's unfortunate as the build I'm planning now has a few very large fans.
tk421 9th October 2009, 13:51 Quote
it's the law of diminishing returns ...

looks like 120 -140mm is the sweet spot, until there is a radical advancement in technology. that's fine with me, 3x 120mm exhausts and 2x120mm intakes is fine.
smc8788 9th October 2009, 14:12 Quote
I'd like to see how multiple smaller fans compare to supersize ones where cases have the option for it (i.e. 2x140mm or 4x120mm).
Kyocera 9th October 2009, 14:22 Quote
The number of tested fans is too low to give any valid conclusion;
the site here recommends ATCS 840, which has one front 230 x 30 mm fan x 1 / 700 RPM / 19 dBA ; one does not know if to change it, with which one.....

The piece on the classic dimensioned fans was great, this here is just to no avail.
SchizoFrog 9th October 2009, 14:26 Quote
Quote:
Originally Posted by smc8788
I'd like to see how multiple smaller fans compare to supersize ones where cases have the option for it (i.e. 2x140mm or 4x120mm).

That would be a totally unfair comparison with 280x140mm2 (39200mm2) compared to 240x240mm2 (57600mm2) which would have a 46% area increase.

(Not exactly true as really you would have to work out the circumfrance area of each individual fan and then time that by 2 or 4 depending on which set up you are looking at... but you get the idea.)
smc8788 9th October 2009, 14:41 Quote
Quote:
Originally Posted by SchizoFrog
That would be a totally unfair comparison with 280x140mm2 (39200mm2) compared to 240x240mm2 (57600mm2) which would have a 46% area increase.

(Not exactly true as really you would have to work out the circumfrance area of each individual fan and then time that by 2 or 4 depending on which set up you are looking at... but you get the idea.)

It may be an unfair comparison, but it would still be an interesting one if your case has the option of one 200mm or multiple 120mm mounts (though the latter would be considerably more expensive), as I don't think it would work to just extrapolate from the single-fan CFM and dBA results.
fathazza 9th October 2009, 14:52 Quote
Quote:
Originally Posted by Kyocera
The number of tested fans is too low to give any valid conclusion;
the site here recommends ATCS 840, which has one front 230 x 30 mm fan x 1 / 700 RPM / 19 dBA ; one does not know if to change it, with which one.....

The piece on the classic dimensioned fans was great, this here is just to no avail.


yeah, as a HAF 932 owner i'd have liked to have seen the coolermaster 230mm fans on the list too. Tho 3 of them in my case do actually create a breeze around my computer area so i dont think i need an upgrade :)
Tyinsar 9th October 2009, 16:59 Quote
Good info. Too bad about the low static pressures. Looks like some of these fans are mostly for show.:(

Yay Antec! ;)
i7lova 9th October 2009, 21:03 Quote
Anyone know what brand of fans the Xclio wind tunnel uses? That's the case I ahve and they seem to move a decent amount of air with not a whole lot of noise and also have speed controls built in.
Otto69 9th October 2009, 21:26 Quote
Bit Tech continues to use the Ghetto fan testing methodology, Until they actually get some real test equipment, and a tester who has some clue as to use it, any further "fan tests" are invalid.
Otto69 9th October 2009, 21:27 Quote
Quote:
Originally Posted by Otto69
Bit Tech continues to use the Ghetto fan testing methodology, Until they actually get some real test equipment, and a tester who has some clue as to use it, any further "fan tests" are invalid.

More to the point: this is like doing CPU heat sink tests using your finger tip as the thermometer.
drakanious 9th October 2009, 21:33 Quote
NO, NO, NO!

This testing methodology is just plain stupid.
Dave Lister 9th October 2009, 22:40 Quote
If i rember correctly (custom pc did a big article with the fans a couple months back) i think they use the black sack method because there is no proper test equipment available, and even the fan manafacturers just make up the cfm and db ratings that they provide
Sparrowhawk 10th October 2009, 00:45 Quote
Quote:
Originally Posted by Otto69
More to the point: this is like doing CPU heat sink tests using your finger tip as the thermometer.

Way to be very negative there, Otto. The theory is sound. You have a container of a known volume, and a fan to inflate that container full of air. As long as there are no major leaks in the cardboard fan shroud, the diaphragm between the cardboard and the plastic bag, or in the bag itself...
Otto69 10th October 2009, 07:03 Quote
As I said in the thread for the last fan "test" using this method; at the very least the fans pressure has to overcome the weight of most of the bag, and of the captive air pushing back against the incoming pressurized air. NEITHER of those things should be present in an actual computer case.
SchizoFrog 10th October 2009, 07:11 Quote
Quote:
Originally Posted by Otto69
As I said in the thread for the last fan "test" using this method; at the very least the fans pressure has to overcome the weight of most of the bag, and of the captive air pushing back against the incoming pressurized air. NEITHER of those things should be present in an actual computer case.

Why not? Does the air inside your case not push back like the rest of ours?
Instead of just complaining like little girls, why not tell us how to do it better? Oh thats right... YOU DON'T KNOW!!! So STFU!!!
Sparrowhawk 10th October 2009, 07:21 Quote
Quote:
Originally Posted by SchizoFrog
Why not? Does the air inside your case not push back like the rest of ours?
Instead of just complaining like little girls, why not tell us how to do it better? Oh thats right... YOU DON'T KNOW!!! So STFU!!!

Agreed. Computer cases have parts which cause a minute amount of air resistance, and the air incoming has to displace the air leaving the case. Then there is the bag issue. All of which are so minute as to vary the test results by probably less than 0.01%. Well within the commonly accepted margin of error for most applications.

PS: No, I don't have a better way of testing. Just throwing that out there.
OleJ 10th October 2009, 16:16 Quote
I have a hard time agreeing with the technique used here.
What if you already have other fans for intake / outtake? Our cases aren't like big black plastic balloons that we wish to inflate.
On the contrary we want to enhance airflow through the case via intake+outtake.
To be fair to these fans you should also measure how long it would take to empty your plastic bag as well. But all in all your method of testing looks flawed for measuring airflow as you have rising air pressure countering the flow.
You should at least do a "fill bag"+"empty bag" and then average that.
I believe you cannot measure the airflow this way unless you calculate lost efficiency based on counterpressure from the confine into which you blow the air.
Quote:
Originally Posted by http://ezinearticles.com/?Fan-Calculations---Measure-Airflow-with-CFM
A standard measurement of airflow indicates how many cubic feet of air passes by a stationary point in one minute. The higher the number, the more air is being forced through the system. The volumetric flow rate of a liquid or gas in cubic feet per minute equals the CFM, and one CFM equals approximately 2 liters per second.

Fan manufacturers base their measurements on a standard measurement with clean, dry air at a density of 0.075 pounds mass per cubic foot, barometric pressure at sea level of 29.92 inches of mercury, and a temperature of 70°F. These standard measurements are used to determine SCFM: Standard Cubic Feet Per Minute.
Quote:
Originally Posted by http://hvac-talk.com/vbb/showthread.php?t=116330

>>Research so far indicates the "garbage bag" method of measuring system airflow at registers is actually comparable...

I've gotta ask you what is this research. I have heard of this method from a Canadian source but have never heard anything good supporting it from this forum. And I think whenever you have a concensus on this board, they tend to be right. For one thing you must measure the seconds to fill, and the precision of your stopwatch will limit the precision (and therefore accuracy) of your CFM figure. If you go ahead and do some measurements this way, I am sincerely eager to hear how it turns out! But in the meantime I have to wonder if there could be better methods.

The one super-amateur method I know of, would use a cardboard box placed over the supply vent, with a measured hole for air to exit. You need the hole large enough that it won't disrupt total airflow much, and small enough that you have a measurable pressure difference between the box and atmospheric. Then you might use a manometer to measure that pressure, and there are equations relating that to airflow. Everything has its drawbacks and this method would certainly be more complicated than the fill-a-bag method. And I have not done it myself, so who knows whether your method might be more practical.

Dwyer makes a pitot tube for use with its manometers, which could be used to measure air speed. By taking various measurements you could get a semi-good measurement of CFM, the pros have a method for this and I better let them describe it. If you are interested of course.

But to get really *good* measurements, the pros use flow hoods costing thousands and those must be calibrated frequently. I really don't think they would do this if a gas-bag method could be developed that would give good enough results.

As I scour the net I find more and more reasons to believe the current method employed is incorrect. Especially in a scenario like the bit-tech one where the current method would probably have a lot smaller margin of error if you were testing high velocity fans like those you use for bathroom ventilation and such.

I think your own results said it best when one of the fans failed to inflate the bag.
OleJ 10th October 2009, 16:29 Quote
You might actually be able to do a ghetto CFM measurement that is a bit more true if you have a cylinder of a certain diameter (larger than the fan blade area) and long enough for the turbulence to become fairly "calm". Then having an anemometer somewhere along the cylinder would probably give you a really good indication of airflow.
I'm not going to draw it in ASCII... you probably understand what I mean. Otherwise PM me and I'll sketch it up for you :) It would be a fairly "cheap" way of doing this.
Maybe it won't work.. I'm not an engineer.. . but it's an idea of how to do it without having to deal with counter pressure.
In short: If you know the volume of a cylinder and you can measure how fast this volume travels then you have your CFM...

In such case you might be interested in the TSI 9515 VelociCalc Air Velocity Meter or something like it.
I found a price for one here: http://www.raeco.com/acatalog/TSI_VelociCalc_AirVelocityMeters_Purchase.html
Not as ghetto as your current rig.. ;-)
Combatus 11th October 2009, 13:01 Quote
Quote:
Originally Posted by Otto69
As I said in the thread for the last fan "test" using this method; at the very least the fans pressure has to overcome the weight of most of the bag, and of the captive air pushing back against the incoming pressurized air. NEITHER of those things should be present in an actual computer case.

So you've not heard of positive and negative air pressure in cases then?
Bufo802 12th October 2009, 09:23 Quote
Does it really matter if the cfm figures are completely accurate (compared to some perfect testing method) if the method provides results which are consistent and able to be compared?
Tyinsar 13th October 2009, 21:32 Quote
Quote:
Originally Posted by Bufo802
Does it really matter if the cfm figures are completely accurate (compared to some perfect testing method) if the method provides results which are consistent and able to be compared?
Agreed

Besides that, I think that such an improvised approach is quite appropriate for a site dedicated to the modding community.
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