Fan Setup

datnoob · 12 May 2015 at 17:37

Hi, i've been reading the forums for a bit but it's my first time posting.

I have a case with space for
2 front 140s or 120s, one open & one obstructed
1 rear & 2 top 120s

the 120s are on the edge of the case so 140s with 120 mounting won't do i think ( Corsair CC-9011050-WW Carbide Series SPEC-01 Mid-Tower ATX Gaming Case )

my card can only hold one fan ( not counting the cpu one ), so i plan on having up to 4 extra ones via the PSU

I am seeking advice on how to set up fans,

2 front 140s, 2 exhaust 120s ?
2 front 120s, 1 exhaust 120 ?
1 front 120 + 1x140, 2 exhaust 120 ?

Looking towards
anoctua f14 pwm for the main front fan
noctua nf a14 flx for the front obstructed one ( the hard drive is behind )
corsair sp120 quiet

What fan setup would you recommend, aesthetics don't matter, the fans will be running full speed on the PSU so the noise matters.

Any other fan recommendation ?

Thank you very much for your help with this ( and for all the other stuff i have read here )

OLDPHART · 12 May 2015 at 19:22

Your fan set up should be so you expel more air than you pull in which gives you a better air flow.

1xrear+2xtop>120mm fans with 2xfront panel.

As for the PSU it should be set to get cool air in your case usually via a air vent in the rear case floor where its fixed.

datnoob · 12 May 2015 at 19:58

Thank you for the quick response :-)

However wouldn't a positive air pressure be preferable over a negative one so as to keep the dust out as much as possible ?

OLDPHART · 12 May 2015 at 20:11

datnoob said:
Thank you for the quick response

However wouldn't a positive air pressure be preferable over a negative one so as to keep the dust out as much as possible ?

Your case has dust filters where needed keeping dust to a minimum, just need to be clean regularly.

datnoob · 12 May 2015 at 20:18

Alright thank you very much !

doyll · 13 May 2015 at 12:20

Much is said about airflow, but most of it has no bases in reality.

A case can only flow as much air as the lessor of the intake or exhaust volume. Simple as that. What goes in must come out .. or .. what comes out must go in. There is no "more exhaust airflow" or "more intake airflow".

Basically, the same applies to "positive pressure" and "negative pressure." It is really "positive airflow" and "negative airflow." If intake has a slightly higher performance than exhaust, the air pressure equalizes by leaking out of case (keeps dust out if all intakes are filtered). But if the exhaust has a slightly higher performance than intake, air leaks into case to balance the pressure (bringing dust in with it.)

Case airflow is all about flowing components' heated exhaust out of case without it contaminating the cool airflow going to components. Sounds simple, but it's not.

More info about case cooling here
http://forums.overclockers.co.uk/showpost.php?p=26159770&postcount=7

I prefer automatic speed control on case fans .. same as on CPU and GPU coolers. Tutorial here
http://forums.overclockers.co.uk/showpost.php?p=26079729&postcount=5

If you want more info or have questions, please ask.

datnoob · 13 May 2015 at 12:32

Thank You very much for the clarification !

ttaskmaster · 13 May 2015 at 13:57

I'd suggest a pair of 140mm on the front intake - Larger fans moving more air at lower rpm = quieter.
Noctuas are pretty good for this and it looks like you're already thinking about the static pressure part. I'm not a 'fan' of SPs, especially the Quiet Editons, personally.

Complement this with three 120mm exhaust fans. You'll want to remove as much warm air as possible. Adding an All-In-One cooler later on could be a good option.

datnoob · 13 May 2015 at 14:37

Yes, i have done some more research and it seems that a popular replacement for the preferable but discontinued Gentle Typhoons is the NB-eLoop B12-2

Would they be fine as exhaust or does this specific usage make them less suitable than something else ? ( i understand that some fans loose in efficiency or gain in noise depending on whether they are used for intake exhaust or radiator ? )

Sorry for my noob questions and thank you for taking the time to help me, i appreciate it.

ttaskmaster · 13 May 2015 at 17:05

datnoob said:
Yes, i have done some more research and it seems that a popular replacement for the preferable but discontinued Gentle Typhoons is the NB-eLoop B12-2

I personally don't rate eLoops, myself - They come in a range of RPMs which just adds more variables, IMO.
The B12-2s are on a noise par with some Noctuas, but pretty low down on the airflow scale. The B12-PS or B12-3 would be a far better choice on both measures.

datnoob said:
Would they be fine as exhaust or does this specific usage make them less suitable than something else ? ( i understand that some fans loose in efficiency or gain in noise depending on whether they are used for intake exhaust or radiator ? )

Case fans and radiator fans are totally different.
Case fans are designed to shift high volumes of air, because their airflow is unrestricted. Radiator fans are designed for high static pressure, ie the ability to force air through an obstruction like a radiator. They won't shift as much air as a case fan, but a case fan will suffer a perpetual compression stall if you put a radiator behind/in front of it.

So in short, if your fan is losing efficiency in one situation over another, it's probably being used incorrectly.
That said, some case fans suffer if you put so much as a grille, dust filter or mesh in front of them.

datnoob · 13 May 2015 at 17:14

Got it, thank you very much for your patience.

Time to get those fans then XD

doyll · 13 May 2015 at 17:43

I have to respectfully disagree with ttaskmaster. Case fans have more in common with radiator and coolers fans than most users realize. Especially now that most cases have dust filters on their intakes and fancy restrictive grills

Having a surplus of static pressure is not a problem, but a fan that cannot overcome the resistance it encounters is worthless.

For example, let us assume a grill and filter created 0.6mm H2O resistnace and we have two fans to test on it.

Fan A is rated 100cfm and 0.6mm H2O and fan B is rated 60cfm and 2.4mm H2O

Fan A will move no air through the filter and grill. At its rated 0.6mm H2O static pressure it move no air .. it is only able to build 0.6mm H2O of pressure before it stops flowing air.

Fan B will be moving about 40cfm through the filter and grill.

Also the slower the fan's rpm, the less airflow and resistance it can overcome.

Static pressure rating is the point the air stops moving .. static = stopped / still .. and it is taken with fan at full speed

ttaskmaster · 13 May 2015 at 18:19

doyll said:
Having a surplus of static pressure is not a problem, but a fan that cannot overcome the resistance it encounters is worthless.

I agree on that, but (decent) case fans should be designed to overcome the minor resistance of grilles, meshes and usually filters.

They are not designed to overcome the major resistance of a radiator grille. Static pressure fans are (usually) designed with a more focussed flow, whereas case fans are meant to blast a load of air in a much wider spread (comparatively). The spread airflow basically bounces off the rad cooling fins instead of going through them, which is what creates the compression stall. It gets much worse if the exhaust side also has a mesh or grille.

Good case fans should/will still have enough SP to force the airflow through. Corsair AF fans are often surprisingly good at this (depending on the rad) and I (mis)use a couple of Noctuas in a similar way.
Conversely, high SP fans will be great at dragging in loads of air through restricted intakes (or through HDD cages), but often won't shift as much as case fans.

But the basic differences still hold up, with case/rad fans each being *better* at their respective design purposes.
At the budget end, it matters a lot, since the fans are unlikely to be that high spec that they will perform well in every position... and at teh other end, if you're going to drop a couple hundred quid on fans, you might as well get the ones designed for purpose.

doyll · 13 May 2015 at 18:56

ttaskmaster said:
I agree on that, but (decent) case fans should be designed to overcome the minor resistance of grilles, meshes and usually filters.

They are not designed to overcome the major resistance of a radiator grille. Static pressure fans are (usually) designed with a more focussed flow, whereas case fans are meant to blast a load of air in a much wider spread (comparatively). The spread airflow basically bounces off the rad cooling fins instead of going through them, which is what creates the compression stall. It gets much worse if the exhaust side also has a mesh or grille.

Good case fans should/will still have enough SP to force the airflow through. Corsair AF fans are often surprisingly good at this (depending on the rad) and I (mis)use a couple of Noctuas in a similar way.
Conversely, high SP fans will be great at dragging in loads of air through restricted intakes (or through HDD cages), but often won't shift as much as case fans.

But the basic differences still hold up, with case/rad fans each being *better* at their respective design purposes.
At the budget end, it matters a lot, since the fans are unlikely to be that high spec that they will perform well in every position... and at teh other end, if you're going to drop a couple hundred quid on fans, you might as well get the ones designed for purpose.

Lots of should, minor, restricted, in there. By the time you get to the end of the post you seem to be pro "radiator" fans for case use.

Shrouds and gaskets between fan and radiator are for good reason. To stop air leaking (spreading) out away from radiator instead of going through it.

Most grills are more restrictive than many think .. from 16-65% .. and that is before filters are added to the airflow restriction. For example the least restrictive round hole punched sheetmetal grill (6mm hole on 8 mm stagger spacing) has 48% open area .. 52% blocked. That's as much or more than many radiators. Hexagonal (honeycomb) 1/4" 9/32" stagger is much better but still only79% open area.

Most "cooler" fans are also marketed as "case" fans.

Same applies to "radiator" fans being sold and used as "case" fans.

There are some decent papers out there about grill and filter resistance. Here are a few.
Vent Grill
http://www.silverstonetek.com/techtalk_cont.php?area=en&tid=wh_chessis

Positive Airflow
http://www.silverstonetek.com/techtalk_cont.php?area=en&tid=wh_positive

Fan Filter Facts
http://www.silverstonetek.com/techtalk_cont.php?area=en&tid=wh12_008

Grill Pattern Effect on sound & airflow
http://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/

Vertical vs Horizontal Airflow
http://www.pugetsystems.com/labs/articles/Vertical-vs-Horizontal-Case-Cooling-89/

ttaskmaster · 13 May 2015 at 20:33

doyll said:
Lots of should, minor, restricted, in there. By the time you get to the end of the post you seem to be pro "radiator" fans for case use.

There *is* a lot of ambiguity, because this isn't as exact a science when it comes to the real world.
There are many different variables, such as the characteristics of the individual case, each individual mounting point, the components within, the fan chosen, selected speeds and the owner's subjective opinion on what is acceptable noise... as well as how all variables combine in each separate instance.

So yeah, in some cases (har har, geddit!) I might indeed advocate a case fan on a rad. It all depends on the exact circumstances and a bit of trial and error often yields better results where the science ought to.

Those are some interesting articles, by the way - Thanks for posting them!

doyll said:
Shrouds and gaskets between fan and radiator are for good reason. To stop air leaking (spreading) out away from radiator instead of going through it.

I meant the air spreading while in between the fins, as in zig-zagging along through the rad the channels resulting in turbulence, rather than a more focussed flow that passes in a straighter line. This turbulence slows the airflow, which builds up back-pressure and stalls against the fan blades, which slows the fan and ultimately reduces the airflow going through the rad.
That is the compression stall and, although I've only experienced fans slowing (in a couple of instances to as much as 30% of their full speed) like this, a properly crap fan might even stop altogether.

So as a general rule, I advocate case for open or less restricted and SP for highly restricted, but with room for experimentation.

CEUOTC · 13 May 2015 at 20:50

To add to this, I have a Corssair H55 AIO cooler fitted in that case, so you will only be able to fit 1 x 120x120x25mm fan in the forward top fan mount. Unless you go for some thin 120mm fans. This maybe due to my H55 having 2x120mm SPs in Push-Pull.

Telecaster · 13 May 2015 at 21:23

ttaskmaster said:
There *is* a lot of ambiguity, because this isn't as exact a science when it comes to the real world.

Oh I think it is, it's called fluid dynamics, it's just that it's beyond most of us and learning it is a lot of work for the sake of a few PC fans.

doyll · 13 May 2015 at 22:02

Telecaster said:
Oh I think it is, it's called fluid dynamics, it's just that it's beyond most of us and learning it is a lot of work for the sake of a few PC fans.

While fluid dynamics may be an exact science, there are so many variables involve in airflow that it is often almost impossible (or just plain impossible) to calculate exact results. We can usually work backwards and figure out all the hows and whys that lead to the results.

Hope that makes sense.

CEUOTC · 16 May 2015 at 13:08

Just fitted 2 x Silverstone SST-FN123 FN Series Fan 1215 - White-Black on the top as exhaust fans, they fit happily above the H55 with Corsair SP120 Twin Pack Red LED Fans (CO-9050029-WW) fitted in push-pull. So have a total of 6 fans fitted, the lowest Corsair AF fan is running off the motherboard, while the rest are running off a NZXT Mesh fan controller. However l planned to replace this with a NZXT Sentry Mix 2 fan controller as the Mesh fan controller can cause my fans to buzz if not fully in the lowest setting when system is set for silent. Use the Sentry Mix 2 on my gaming rig and it is leagues ahead of the Sentry Mesh imo.