Bigger doesnt equal better?

[Adragontattoo]

Ok, so I am going through all the fans I have stripped from cases, power supplies and machinery I have gutted and I am wondering something.

Is anything over an 80-92mm fan really necessary for a blowhole(blowing out not in)?

Reason behind my thinking is this, the blowhole is not actively cooling anything. Its entire function is to take any air that has escaped the airflow setup in your case and blow it out the top. If your case is effectively configured a silent or near silent 80mm fan would arguably do the exact same job as a higher flow fan.

Regardless of the negative or positive pressure configuration of your case, I dont see how a larger fan would realistically give any improvement over a 80mm or possible smaller fan (assuming it is quiet).

Would a perforated top panel give better performance then any fan due to the width of the fan and dead air that isnt being moved around at all?

[DareDevil_747]

Usually, the reason people use larger fans is not because they can move more air, its because they can move the same amount of air an 80/92mm will, with a lot less noise.
However, I am a firm believe that more air = better cooling, even with an exhaust fan. All the air that gets blown out of the top of your case, has to be replaced with cool air drawn in from the outside. The more air ur exhaust fan moves, the less time the hot air inside the case has to linger around and keep things hot.
Can u rephrase ur last question about the perforated top panel?

[Adragontattoo]

ok, Heat rises, plain and simple. Wouldnt a perforated top work better at exhausting ALL hot air then any fan.

[Adragontattoo]

Usually, the reason people use larger fans is not because they can move more air, its because they can move the same amount of air an 80/92mm will, with a lot less noise.
However, I am a firm believe that more air = better cooling, even with an exhaust fan. All the air that gets blown out of the top of your case, has to be replaced with cool air drawn in from the outside. The more air ur exhaust fan moves, the less time the hot air inside the case has to linger around and keep things hot.
Can u rephrase ur last question about the perforated top panel?

More air doesnt really equal better cooling though. Having fans where they need to be and having your wires managed so that you get ventilation and adequate airflow is going to do more for your temps inside the case then having your entire sidepanel be full of fans though wouldnt it? Everyknow knows by know the hotspots in a case. Hdd, CPU, GPU NB/SB and to an extent memory are the main contributors of heat (PSU isnt being counted in this assumption). Having adequate ventilation blowing in cool air should do more for cooling then having an oversized fan exhausting the "hot" air. I am not saying that a blowhole isnt needed, I just question if anything over 28CFM (figuring a silent 80MM) is probably overkill.

[Anjow]

But if you have a silent 80mm moving 28cfm, then you could get a silent 120mm moving more?

[Adragontattoo]

but do you need more is the question. What is the use of a high CFM low DB fan if the other fans are doing like they should be and pushing incoming air over the heat producing portions?

This is probably something that everyone has their opinion and without alot of testing using idfferent configurations in the same case you wouldnt get a definitive answer.

[techun]

if you're not sure, just use the bigger fan? lol

that way you can really CRANK it if you need to

[Electron Chaser]

but do you need more is the question. What is the use of a high CFM low DB fan if the other fans are doing like they should be and pushing incoming air over the heat producing portions?

This is probably something that everyone has their opinion and without alot of testing using idfferent configurations in the same case you wouldnt get a definitive answer.

Well that heated air that you moved over the heat producing portions has be evacuated out of the case otherwise the a portion of that air gets recycled back over the same heat producing components. So the faster you get that warm air out of there the more cool air can come in to take it's place

[R4z0r4mu5 Pr|m3]

i agree with DareDevil_747, when air is exhausted, cool air from outside the case is automatically drawn in from vents but evenly as not to contribute to a lot of dust accumulating in the case, when you use an intake fan, it pulls air in at one spot with great suction and draws in a lot of dust that can accumulate in the heatsinks and what not and drive temperatures up in the long run, of course you can use a filter that you can clean every week though but why bother when an exhaust fan is an all in one solution for quiet pc uses

[Adragontattoo]

in Quiet PC use yes I can see getting the biggest CFM lowest DBA fan but what I am referring to is Gaming PC's or PC's that you arent going for the quietest possible unit.

[DareDevil_747]

Like they said... yes putting a fan on top will help... yes heat does rise, BUT it rises slowly. Sooo, like, all that hot air that the HSF on ur GPU just pulled out will start to slowly rise... then get sucked into the CPU's HSF, cooling ur CPU with warm air... then the CPU gets done with it and it still rises, and (in an NF4 system) lingers around the memory... and gets even hotter, then slowly keeps rising until it slowly makes it out the top of the case....
Stick a (i'll recommend a fan here) AeroCool Xtreme Turbine 120mm 90CFM fan on top to pull all that hot air up and out of the case, then, all those components willl get cool air from the intake fan a LOT faster, resulting in a cooler overall system.
I understand what u are thinking, heat does rise, but, nowadays these systems generate a heck of a lot of heat... so adding more exhaust fans can only benefit you. You have to think of it from a "volume" perspective. Theres a certain amount of cubic inches of airspace in ur case. For all the CI's of hot air you pull out of that case with an exhaust fan/s, its replaced with the same amount of CI's of cool outside air.
Ultimately, the main goal here is to get the hot air OUT. The more exhaust fans u have, or the bigger, faster ones, just gets it out faster.

EDIT: The reason I recommended that fan is because its cheap, quiet, and effective. I just bought 3 for my other system, wanted something quieter than these tornadoes I have in this system, and these are 16 blade fans, extremely good-looking, and create phenominal pressure. I might be mistaken, but if I remember right, these are rated under 50 dB... and sounds quieter than that... and 90CFM should be enough for almost anyone, especially for case fans.