1. The formula comes from bench testing on our test bench case w/ 16 fans and using a fog machine. We set it up in various scenarios and then directed the fog at the rear case grille, observing whether the fog was sucked in thru or blown away from the rear case grille.
2. I should note that the test bench is my personal 24/7 rig used for AutoCAD during working hours, gaming in doing nerdy stuff like this on off hours. It's normal set up is as follows:
CHA_1 MoBo Header = Fan Contol PCB No. 1 =>(6) 140mm intake fans on 420mm Radiator
CHA_2 MoBo Header = Fan Contol PCB No. 2 =>(4) 140mm intake fans on 280mm Radiator
CHA_3 MoBo Header = Fan Contol PCB No. 3 =>(5) 140mm case intake fans and (1) 140mm exhaust fan
All fans are 1250 rpm standard pressure fans, each channel has separate set points for turning off the fans when CPU temps below a certain point and a temperature / speed curve above that .
It should be noted that there is no need for both intake and exhaust fans ... the designation is dictated solely by the location. Air is pushed in thru the front and out the back so as to not blow hot air at the user. The rear fan is an exhaust because otherwise it would suck air in thru rear vents.
Think about it ... my home / office is in a 175 year old dairy barn with office in what once the hay loft ... It has an attic fan used in the summer to remove heat from the building. So if this rather large building doesn't need any intake fans, why would a PC case, tiny by comparison, need "matching ins and outs" ?
Why doesn't a kitchen exhaust hood have a "matching" intake fan ? why not in a restaurant or office space ? Fans create pressure (negative / positive) in an enclosed space ... you don't need anything else but a hole in the wall to create air flow. When I use the attic fan above the highest level in the building, I open a window on the lowest level in the building and it works.
In a PC, you can create the same effect using all intakes or all exhausts ... you will want all intakes to be filtered and you don't want to out an intake fan above the PSU and GFX card exhaust.
3. High static are a left over relic from the days of 30 fpi radiators tho still useful today for CLC radiators, Otherwise, Hi SP / Hi rpm fans really do not bring anything to the table except a ton of noise. Of course in a teeny case with insufficient fan mounts, this may be your only option. Putting Hi SP fans on exhaust is not a good idea.... if anything the place where you could argue they might be needed is on the intakes where they could overcome the restriction from the filter itself as well as any dust clogging it. But the fact remains, there is no need for Hi SP fans unless you don't have the necessary mounting locations.
Looking at his build, he has about 375 watts of heat to exhaust on overclocked box (120 watt CPU, 190 watt GFX, 30 watts MoBo, 35 watts everything else) and rule of thumb for a quiet box (standard pressure, low rpm) is 50 - 75 watts per 120mm fan. 375 / 75 = 5 fans
4. Corsair fans have several issues...
a) When PWM are used, they have a problem when ganged on a single channel, they lose fan speed control. Tech Diva Darlene says it better than most ... if you want to be awed, take a look at some of her builds on OCN.
b) Other than that, while decent, they are by no means the best. Among cooling enthusiasts Noctua AF and Gentle Typhoon series where considered the two contenders for best fans.... but eventually the kings passed on and a new one was crowned. See chart here
http://www.silentpcreview.com/article1345-page7.html
Here we see what happens when you take a Noctua air cooler and replace the Nocuta fans with Phanteks ... at same rpm, CPU temps drop 6C.
http://www.overclockersclub.com/reviews/phenteks_f140/3.htm
In short, you go to a high SP fan when you have static pressure to overcome as in a radiator with very tight fin spacing. PC cases do not present that unless you have a very small, cluttered case that must push a ton of air because of insufficient fan mount locations. The downside of course to hi SP / Hi rpm is noise as we saw in the video from last post. If user was to use 3 fans (2 in / 1 out) a MP fan (1500 -1650 rpm) might serve better, but w/ 6 fan locations, you can have a dead silent case using 1250 rpm fans and controlling fan speeds from 350 - 850 rpm, tho you won't likely get over 600 rpm outside of stress testing scenarios... a good fan will be unaudible below 850 rpm.
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