[SOLVED] Fan setup, looking for optimal airflow

Exeonx

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So after carefull considering I'm planning on getting an Asus TUF GT501 PC case.
I'm wondering what kind of fan setup I should aim for, as far as capacity goes itt has 3x120mm/2x140mm front options, 3x120mm/2x140mm top and 1x140mm rear.
I hear that I'm best off doing positive pressure, however if I fill all slots that's hardly possible, I'd have negative pressure, my GPU will also be the blower type and it will exhaust a lot of air on it's own.
My CPU cooler is the Noctua DH-15, the fans are also quite high for airflow.
Since I'm planning to install ARGB fans, depending on the models the airflow they provide ranged from poor to "ok"

Any kind of recommendation for this setup?
Is there a specific amount of CFM I should look for in the fans?
I could technically get different brands of fans to help with the amount of CFM, but I'm worried how it'll look in my system.
 
Solution
So basically fan pressure (rated in mmH2O?) > CFM
Makes sense, airflow without any resistance is meaningless with things like dust filters
To the first one, that's not always true.
As for the 2nd one: ??? A dust filter is a point of resistance.
There's many different fan combinations, but they all fall into one of a few categories:
A)Airflow
Typically have low static pressure, so are not ideal for use on radiators and heatsinks. Has the telltale large gaps between their blades. Example: Noctua NF-S12A and S12B.
They can be used as chassis intake, but only if the panel they're pulling air though is open mesh - they quickly lose efficiency otherwise.
As chassis exhaust, they can't be beat, if only because the areas intended for...

Phaaze88

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Any kind of recommendation for this setup?
You need to be willing to do your own testing. What works best will vary based on:
-chassis design
-the hardware you're cooling
-the coolers that are mounted to your hardware
-the kinds of fans you're using and how fast you'll run them normally
The general recommendation of 'front to back, bottom to top', airflow path, is the jack of all trades setup; you can't go wrong with it, except in rare situations.

I could try and guess, based on my experience, and still be wrong on what will work best:
-depending on fan specs, 3x120mm/2x140mm front intake
-if the rear fan is weaker(in specs) than the ones on the NH-D15, do not use it, as it will get in the way
That's it.

The top, you say? Well, I suspect fans up there won't be very effective, because:
-the design adds more air resistance, reducing the effect of any placed there.
-the D15 already pulls air from up there, along with its supply from the front; top fans, whether intake or exhaust, will just get in the way.
-the D15's folded heatsink design promotes a more uniform front to back airflow path and reduces the effect(again) of fans placed above it.
-since the blower gpu dumps it's waste heat right out the back, top fans are, yet again, less useful. Top fans are handy for helping to remove the heat from the axial fan cooled models that dump their heat inside the chassis instead.

Is there a specific amount of CFM I should look for in the fans?
No, because it doesn't mean anything on its own.

I could technically get different brands of fans to help with the amount of CFM, but I'm worried how it'll look in my system.
Best to stick with one fan.
Also, decent LED fans don't come cheap - the cheap ones don't have any real muscle to them.
LEDs are not free. Manufacturers want to stay within a certain power budget, and the thing that gets sacrificed is fan strength; if a particular model has both LED and non LED variants, the non LED will always be stronger.
 

Exeonx

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You need to be willing to do your own testing. What works best will vary based on:
-chassis design
-the hardware you're cooling
-the coolers that are mounted to your hardware
-the kinds of fans you're using and how fast you'll run them normally
The general recommendation of 'front to back, bottom to top', airflow path, is the jack of all trades setup; you can't go wrong with it, except in rare situations.

I have no issues stress testing my system to find the optimal way of running, I do understand this may be different case by case
I could try and guess, based on my experience, and still be wrong on what will work best:
-depending on fan specs, 3x120mm/2x140mm front intake
-if the rear fan is weaker(in specs) than the ones on the NH-D15, do not use it, as it will get in the way

That's a good point, the noctua fans are rated for 140CFM and there are 2 off them on the cooler
The highest rated 140mm ARGB fan (for airflow) that I could find is the "Fractal design prisma PWM " which "only" reaches 103CFM
So I guess I should just ditch the rear fan alltogether

The top, you say? Well, I suspect fans up there won't be very effective, because:
-the design adds more air resistance, reducing the effect of any placed there.
-the D15 already pulls air from up there, along with its supply from the front; top fans, whether intake or exhaust, will just get in the way.
-the D15's folded heatsink design promotes a more uniform front to back airflow path and reduces the effect(again) of fans placed above it.

Best to stick with one fan.
Also, decent LED fans don't come cheap - the cheap ones don't have any real muscle to them.
LEDs are not free. Manufacturers want to stay within a certain power budget, and the thing that gets sacrificed is fan strength; if a particular model has both LED and non LED variants, the non LED will always be stronger.

Well I'd still like some lighting on the top part of the case.
Considering it doesn't add any real value, would it be an option to use lower performing fans on the topside so it doesn't clash with the NH-D15?
I have noticed that LED's fans indeed don't come cheap, however more expensive models don't mean more airflow.
Corsair made some of the fans with the most adressable LED's, but their performance is worse than a lot of the cheaper models.

-since the blower gpu dumps it's waste heat right out the back, top fans are, yet again, less useful. Top fans are handy for helping to remove the heat from the axial fan cooled models that dump their heat inside the chassis instead.

There is one last thing I forgot to mention.
I'm getting the RTX3080 at some point (whenever my order gets through the queue)
This is the ASUS TUF edition, from what I saw in reviews although some air gets gets blown through most heat goes to the top.
With the case I'm also able to mount it vertically, which I'm more than willing to do if it aids airflow in any way.

You do make quite some excelent points, so thanks a lot for the help.
My current case is just made for maximum airflow, having 3x200mm and 3x140mm fans, but I no longer need so much airflow, in the past ambient temperatures would get up to 40C, now it doesn't go beyond 25C
 

Phaaze88

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CFM doesn't mean anything on its own.
A)Manufacturers design their fans around 100% rpm, so the ratings you see only apply at that speed.
But they don't post fan curves, so no one can tell how fans behave at a given speed below 100%; and hardly anyone runs their fans at that speed these days, so we're left guessing...
Or someone can go out of their way to test a crap ton of fans...

B)There's static pressure: a fan's ability to 'stand up' to obstacles. The higher it is, the less CFM it loses in the face of said obstacles.

C)Noise level(dBA). This doesn't scale linearly. But even if the user gets 'low noise' fans, there's a potential problem...
Noise frequency(Hz). People have certain sounds they can't stand, which varies between individuals. Example:
While Noctuas are pretty high quality fans, some people can't stand the humming of the motor. All I have are Noctua fans, and I've never noticed this annoying hum. It could happen with any brand of fans, I'd imagine.

Well I'd still like some lighting on the top part of the case.
Considering it doesn't add any real value, would it be an option to use lower performing fans on the topside so it doesn't clash with the NH-D15?
I have noticed that LED's fans indeed don't come cheap, however more expensive models don't mean more airflow.
Corsair made some of the fans with the most adressable LED's, but their performance is worse than a lot of the cheaper models.
LED strips then? Though, I'm not familiar with using any.

There is one last thing I forgot to mention.
I'm getting the RTX3080 at some point (whenever my order gets through the queue)
This is the ASUS TUF edition, from what I saw in reviews although some air gets gets blown through most heat goes to the top.
With the case I'm also able to mount it vertically, which I'm more than willing to do if it aids airflow in any way.
Oh... well, you did mention blower gpu in your first post...
Yeah, the Asus TUF is going to change what works best in that chassis. See the fins of the heatsink? Those guide the air that the fans push into it.
It goes out the sides and multiple things happen at once when it hits those walls(motherboard and side panel):
-circles downward and gets sucked back into the gpu
-circles upward and gets pulled out of the chassis
-circles upward and gets pulled into the cpu cooler(regardless of the type) before making its way out of the chassis
-absorbed by the motherboard
-absorbed by the side panel
^Well, that's all horizontally, at least.

Vertically can work, as long as you do not use the vertical slots provided with the chassis - at least with air cooled graphics cards. There are kits that use the horizontal PCIe slots.
Anywho, what's going to happen to the air here:
-ejected towards the psu shroud and circles its way back into the gpu
-ejected upwards and gets pulled out of the chassis
-ejected upwards into the cpu cooler before making its way out of the chassis
-absorbed by the psu shroud
^Doesn't look all that different from horizontal, but there is a larger volume of heated air circling back into the gpu in this orientation. Plus, the fans are facing the side panel directly - produces a little more noise compared to horizontal.

ambient temperatures would get up to 40C, now it doesn't go beyond 25C
All this really affects are idle thermals. Under a reasonable load, it affects next to nothing.
 

Exeonx

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CFM doesn't mean anything on its own.
A)Manufacturers design their fans around 100% rpm, so the ratings you see only apply at that speed.
But they don't post fan curves, so no one can tell how fans behave at a given speed below 100%; and hardly anyone runs their fans at that speed these days, so we're left guessing...
Or someone can go out of their way to test a crap ton of fans...

B)There's static pressure: a fan's ability to 'stand up' to obstacles. The higher it is, the less CFM it loses in the face of said obstacles.

So basically fan pressure (rated in mmH2O?) > CFM
Makes sense, airflow without any resistance is meaningless with things like dust filters

LED strips then? Though, I'm not familiar with using any.

I detest LED strips, I hate seeing the individual LED's on them, gives me a "cheap" look (In my mind at least)
The only ones I really like are the cooler master LED Bar's, Example:
https://www.amazon.de/-/en/Cooler-U...&replacementKeywords=cooler+led+leiste&sr=8-1
These are magnetic and don't use things like USB connection, they also give a glow like old tubes use to, they exist in ARGB form but they always seem to be sold out

Oh... well, you did mention blower gpu in your first post...
Yeah, the Asus TUF is going to change what works best in that chassis. See the fins of the heatsink? Those guide the air that the fans push into it.
It goes out the sides and multiple things happen at once when it hits those walls(motherboard and side panel):
-circles downward and gets sucked back into the gpu
-circles upward and gets pulled out of the chassis
-circles upward and gets pulled into the cpu cooler(regardless of the type) before making its way out of the chassis
-absorbed by the motherboard
-absorbed by the side panel
^Well, that's all horizontally, at least.

Vertically can work, as long as you do not use the vertical slots provided with the chassis - at least with air cooled graphics cards. There are kits that use the horizontal PCIe slots.
Anywho, what's going to happen to the air here:
-ejected towards the psu shroud and circles its way back into the gpu
-ejected upwards and gets pulled out of the chassis
-ejected upwards into the cpu cooler before making its way out of the chassis
-absorbed by the psu shroud
^Doesn't look all that different from horizontal, but there is a larger volume of heated air circling back into the gpu in this orientation. Plus, the fans are facing the side panel directly - produces a little more noise compared to horizontal.

Yea sorry about that, I was under the impression that the RTX3080 would be the same, but I got reminded in a video that it's not the same at all.
I see, but does this change what a more ideal fan setup would be? I could also look to make my NH-D15 blow upwards(rather than facing the rear exhaust) with the 3080 mounted vertically for instance.
I'm not bothered by a bit more sound in my PC, my current one is all mesh, and I have my headphones cranked up most of the time.
 

Phaaze88

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So basically fan pressure (rated in mmH2O?) > CFM
Makes sense, airflow without any resistance is meaningless with things like dust filters
To the first one, that's not always true.
As for the 2nd one: ??? A dust filter is a point of resistance.
There's many different fan combinations, but they all fall into one of a few categories:
A)Airflow
Typically have low static pressure, so are not ideal for use on radiators and heatsinks. Has the telltale large gaps between their blades. Example: Noctua NF-S12A and S12B.
They can be used as chassis intake, but only if the panel they're pulling air though is open mesh - they quickly lose efficiency otherwise.
As chassis exhaust, they can't be beat, if only because the areas intended for exhaust present the least resistance of any other areas in a chassis.

B)Static pressure
Typically have low CFM, but often can be observed moving more air than airflow fans, except on open test beds - because there's like, no obstacles in that scenario. Smaller gaps between the blades. Example: Noctua NF-F12, and P12.
Hands down, these have more utility than airflow models; in a chassis, there's always obstacles present, so there's no harm in only using static pressure fans throughout your chassis.

C)All-around
Best of both worlds, master of neither. You know, the good middle ground. Example: NF-A14, A15, and A12x25.
Downside? $$$.

I detest LED strips, I hate seeing the individual LED's on them, gives me a "cheap" look (In my mind at least)
The only ones I really like are the cooler master LED Bar's, Example:
https://www.amazon.de/-/en/Cooler-U...&replacementKeywords=cooler+led+leiste&sr=8-1
These are magnetic and don't use things like USB connection, they also give a glow like old tubes use to, they exist in ARGB form but they always seem to be sold out
Sorry. I'm not a fan of LEDs, so I saw them as the same thing.
Supply is probably a combination of demand and Covid.

Yea sorry about that, I was under the impression that the RTX3080 would be the same, but I got reminded in a video that it's not the same at all.
I see, but does this change what a more ideal fan setup would be? I could also look to make my NH-D15 blow upwards(rather than facing the rear exhaust) with the 3080 mounted vertically for instance.
I'm not bothered by a bit more sound in my PC, my current one is all mesh, and I have my headphones cranked up most of the time.
Hmm...
I would leave the NH-D15 in the horizontal position. It doesn't pull in as much of the gpu's exhaust that way Vs the vertical position, where it would be more 'centered' over the gpu.
A)Front: 3x 120/2x 140mm - example: 3x NF-F12/2x NF-A14
As far as surface area goes, the 3x 120s would be better, but then I'd have to question how useful that is with the psu shroud.
I think 2x 140 is better here.

B)Rear: 120/140mm
This one's easy, the 140mm hands down.

C)Top: 3x 120/2x 140mm - example: 3x NF-S12A/2x NF-A14
The 3rd party coolers may cool better than the blower and FE models, but they do so while screwing over the cpu cooler - whether air or liquid.
2x 140 is better here, 3x 120 with crazy long gpus.
You might say, "What if I just put one fan at the top-rear?" Well, it'll help cpu temps some, but now it's takes a little longer to get the gpu heat out. You may as well focus on the higher power consuming gpu.
It's all a balancing act.
 
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Exeonx

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Hmm...
I would leave the NH-D15 in the horizontal position. It doesn't pull in as much of the gpu's exhaust that way Vs the vertical position, where it would be more 'centered' over the gpu.
A)Front: 3x 120/2x 140mm - example: 3x NF-F12/2x NF-A14
As far as surface area goes, the 3x 120s would be better, but then I'd have to question how useful that is with the psu shroud.
I think 2x 140 is better here.

B)Rear: 120/140mm
This one's easy, the 140mm hands down.

C)Top: 3x 120/2x 140mm - example: 3x NF-S12A/2x NF-A14
The 3rd party coolers may cool better than the blower and FE models, but they do so while screwing over the cpu cooler - whether air or liquid.
2x 140 is better here, 3x 120 with crazy long gpus.
You might say, "What if I just put one fan at the top-rear?" Well, it'll help cpu temps some, but now it's takes a little longer to get the gpu heat out. You may as well focus on the higher power consuming gpu.
It's all a balancing act.

Allright, thanks for all the advice man, I really appreciate it.
Would you mount the GPU vertically or horizontally with this setup? Or does it not influence the airflow in this scenario?
 

Phaaze88

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Would you mount the GPU vertically or horizontally with this setup?
Personally speaking, I'd go vertical if doing it with a hybrid cooler or custom liquid gpu in there.
Even though I know there's space to do it, it doesn't sit right with me to do it with an air cooled model.

Or does it not influence the airflow in this scenario?
Oh, it does indeed influence the airflow - primarily below the gpu in this scenario.
As I mentioned earlier: because of the psu shroud, vertical with the TUF 3080 will see a larger volume of exhaust circulating back into the cooler, so it'll run a little warmer - nothing dangerous, unless the card was already running toasty for some unknown reason.
It could also run a little louder, since the fans are facing the side panel.
 

Exeonx

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Personally speaking, I'd go vertical if doing it with a hybrid cooler or custom liquid gpu in there.
Even though I know there's space to do it, it doesn't sit right with me to do it with an air cooled model.

Oh, it does indeed influence the airflow - primarily below the gpu in this scenario.
As I mentioned earlier: because of the psu shroud, vertical with the TUF 3080 will see a larger volume of exhaust circulating back into the cooler, so it'll run a little warmer - nothing dangerous, unless the card was already running toasty for some unknown reason.
It could also run a little louder, since the fans are facing the side panel.

Allright thanks for the info, I'm still undecided on this part, I was leaning towards mounting it vertically even with air.
I believe Aestetically speaking the TUF card will combine quite well with the TUF case.
However I'm not willing to increase GPU temperatures just for mounting it differenty, 1-2C's under load would be acceptable but 5 or more wouldn't be.

I guess I'll test this at some point and get the custom vertical setup (rather than what the case offers) if I like it
 

Karadjgne

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Airflow = high cfm, low sp.
Balanced = ok cfm, ok sp.
Pressure = low cfm, high sp.

In a nutshell, a Airflow fan will move ALOT of air, but a Pressure fan will MOVE alot of air. Pressure/balanced are best as intakes, they have enough force behind the mediocre cfm to move Alot of it to the back of the case, namely feeding the gpu. Airflow fans are best at exhausts, nobody cares about where the exhausted heat/air goes or how far it goes, as long as it's gone from the case.

A pressure fan with 30cfm, will put most of that 30 at the gpu, generally the highest heat output in a gaming cpu. An airflow fan with 50cfm will flood the front of the case better, but may only get 10-15 worth over to the gpu.

That's where balanced fans come in. Enough sp to get a good chunk over to the gpu, but also high enough cfm to flood the case.

But that's not counting restrictions, like dust filters, hdd bays etc. Obstructions such as that make it more important to have higher pressure, force the air past/around.

Vertical gpus air-cooled is usually an issue. Very few cases or even custom mounts allow for taller shrouds, you are generally restricted to a 2x card, because taller puts the fans too close to the side panel and the gpu starves for air. Using an over/under design like the FE could complicate that as the intake fan is the one all the way to the rear, the exhaust fan siphoning any incoming air and rerouting it back towards the motherboard.

Form/fit and function are quite often polar opposites, especially stuff done on a whim without some serious amounts of homework
 
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Exeonx

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Personally speaking, I'd go vertical if doing it with a hybrid cooler or custom liquid gpu in there.
Even though I know there's space to do it, it doesn't sit right with me to do it with an air cooled model.


Oh, it does indeed influence the airflow - primarily below the gpu in this scenario.
As I mentioned earlier: because of the psu shroud, vertical with the TUF 3080 will see a larger volume of exhaust circulating back into the cooler, so it'll run a little warmer - nothing dangerous, unless the card was already running toasty for some unknown reason.
It could also run a little louder, since the fans are facing the side panel.

Allright
I actually decided to not get ARGB fans, rather I'll get the phantek halo's to put over them.
I'll probably be reusing some of my higher performing noctua fans and probably adding some more of them


Airflow = high cfm, low sp.
Balanced = ok cfm, ok sp.
Pressure = low cfm, high sp.

In a nutshell, a Airflow fan will move ALOT of air, but a Pressure fan will MOVE alot of air. Pressure/balanced are best as intakes, they have enough force behind the mediocre cfm to move Alot of it to the back of the case, namely feeding the gpu. Airflow fans are best at exhausts, nobody cares about where the exhausted heat/air goes or how far it goes, as long as it's gone from the case.

A pressure fan with 30cfm, will put most of that 30 at the gpu, generally the highest heat output in a gaming cpu. An airflow fan with 50cfm will flood the front of the case better, but may only get 10-15 worth over to the gpu.

That's where balanced fans come in. Enough sp to get a good chunk over to the gpu, but also high enough cfm to flood the case.

But that's not counting restrictions, like dust filters, hdd bays etc. Obstructions such as that make it more important to have higher pressure, force the air past/around.

Vertical gpus air-cooled is usually an issue. Very few cases or even custom mounts allow for taller shrouds, you are generally restricted to a 2x card, because taller puts the fans too close to the side panel and the gpu starves for air. Using an over/under design like the FE could complicate that as the intake fan is the one all the way to the rear, the exhaust fan siphoning any incoming air and rerouting it back towards the motherboard.

Form/fit and function are quite often polar opposites, especially stuff done on a whim without some serious amounts of homework


This explination makes a lot of sense, you can move a lot of air but if at the slightest obstruction it stops moving it can be worthless, or if it can't get the air past the dust filter due to low pressure.

I do notice though that in quite some cases if airflow increases then so will pressure, it comes down to the brand a lot though.
I see that Noctua makes quite highly speced fans, if you can get behind the price tag and color scheme.

I do still worry that no matter what I'll get a negative pressure in my case, more air being exhausted than intake.
 

Karadjgne

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Just about all HP, Lenovo, Sony, Compaq etc etc prebuilts are single fan in rear, negative pressure pc cases. Have been for years.

Ppl make it sound like negative is to be avoided at all costs. That's impossible. At idle, you will have a negative system unless All your fans are intakes because the cfm of a low rpm fan isn't really enough to do anything. You'll only get cfm at higher rpm.

Linustech did a 1 year study, 6 identical pc's in the basement where he was revamping his studio. Plenty of drywall dust etc. The only differences in the pc's was fan orientation. A full intake at one end and a full exhaust at the other.

His conclusions were simple. Positive or negative really didn't make any difference to dust accumulation, the microfine dust particulate going through the dust filters just as readily as without one. What did make a difference was Where the dust accumulated, and that depended on the airflow patterns and placements of the fans.

Negative pressure won't affect anything vs positive, what will is where your fans are, the curves they are set to and what obstructions to airflow channeling you have.
 
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Karadjgne

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Heh, not really. Gotta look at the physics. Dust is not all 1 size. You get everything from pet hair to pet dander to skin flakes to dust so fine and light it takes a week to drop 3 feet. It's why they sell different types of ac filters, some are finer mesh than others.

With pc's, fans are so pathetic when it comes to suction power that dust filters have rather large (comparatively) holes. There's a lot of dust that's smaller than those holes that passes straight through. About the only thing a dust filter stops is the larger particulate. They'll slow down dust accumulation, not prevent it.

Being as your pc is going to get dusty, no matter what you do, does it really make much difference if you blow it out every other month with a filter, or every other month without a filter.