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Guru Meditation
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15 Posts
Discussion Starter #1
So here's the thing.

After choosing an AIO (Celsius S36) for my latest build, air flow in my case has decreased. Not to the point that it's an actual concern, as temps are perfectly fine, but I'd like to see if I can improve them. My old set-up, with excellent air flow, was this:

Lian Li D8000 case
6 x 120mm intake fans towards the front, 3 on either side
4 x 140mm exhaust fans at the rear

The current set-up is this:

Lian Li D8000 case
6 x 120mm intake fans towards the front, 3 on either side
1 x 140mm exhaust fan at the rear
Celsius S36 exhausting at the rear

The trouble is that the Celsius is obviously far less efficient as an exhaust compared to the previous 3 140mm fans, both because its fans are smaller and because they often run quite slowly. The only other place where fans can be fitted is in the top of the case, where I can swap in mounts for an additional 2, or 2 x 2, 140mm fans.

Adding 2 intake fans would obviously do little to nothing, as I already have more air coming in than is being exhausted. However, adding two exhaust fans is something I'm loath to do, as I want to keep positive pressure inside the case.

So my question is this: how effective would it be to add two intake fans and two exhaust fans to the top of the case, sitting side by side? Hopefully someone here is more conversant with thermodynamics than I and can offer some insight....
 

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Premium Member
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682 Posts
So here's the thing.

After choosing an AIO (Celsius S36) for my latest build, air flow in my case has decreased. Not to the point that it's an actual concern, as temps are perfectly fine, but I'd like to see if I can improve them. My old set-up, with excellent air flow, was this:

Lian Li D8000 case
6 x 120mm intake fans towards the front, 3 on either side
4 x 140mm exhaust fans at the rear

The current set-up is this:

Lian Li D8000 case
6 x 120mm intake fans towards the front, 3 on either side
1 x 140mm exhaust fan at the rear
Celsius S36 exhausting at the rear

The trouble is that the Celsius is obviously far less efficient as an exhaust compared to the previous 3 140mm fans, both because its fans are smaller and because they often run quite slowly. The only other place where fans can be fitted is in the top of the case, where I can swap in mounts for an additional 2, or 2 x 2, 140mm fans.

Adding 2 intake fans would obviously do little to nothing, as I already have more air coming in than is being exhausted. However, adding two exhaust fans is something I'm loath to do, as I want to keep positive pressure inside the case.

So my question is this: how effective would it be to add two intake fans and two exhaust fans to the top of the case, sitting side by side? Hopefully someone here is more conversant with thermodynamics than I and can offer some insight....
That sounds a bit complicated. There are so many factors that come into account with air flow, fans, case. Speed of fans, static pressure, filters, tempered glass front panels, and etc. Having fans in push/pull isn't going to double the air flow. Between all that I wouldn't be surprised if 1 fan would be fine as exhaust. You will have positive pressure in your case, though restrictions from what I mentioned above can effect that. Generally exhaust fans have less restrictions than intake. I think adding more fans might not improve things and make things worst if you are planning on doing it from the top as an intake as well as exhaust setup. Having airflow from one part of the case is a very good setup. You can wet a finger and put it up to a non-fan vent to see if you can feel anything blowing, same to the top. I am planning on redoing my setup as well. There is way to much to consider, especially if you have a custom loop like I do w/ a 360mm and a 240mm ><.

In all there are way to many variables. The best option is to experiment and use watts at wall, ambient temps, and temps in various parts of your setup to help make you decision.
 

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Guru Meditation
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15 Posts
Discussion Starter #3
Thanks mate, I appreciate the insight. Sadly it's my feeling too that it's likely a question only experimentation can answer. That being the case I guess I'll just leave things as they are. I'm not too keen on shelling out for 4 140mm fans only to find that temps are still at status quo.
 

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Premium Member
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682 Posts
Yeah, I think your current setup is the best route from a complete guess. You are not getting 6:1 ratio on fans as your stacking and that doesn't double it. Generally intake fans have the most obstructions and exhaust generally just have a honey comb.

I too am thinking of redoing my loop and fans, putting 3 high pressure 120mm fans in front as intake on high FPI rad and run 2x120mm pushing a rad at really slow speeds on top (low FPI rad) and maybe 3rd exhaust at a very slow speed as well. I might just go with the two top fans only. I would love to see some multiple sets of data from multiple cases in 3x120mm fans. I am waffling on fans for the front. I want more than 2mmh20 of static pressure, I don't want something to loud, and I want digital RGB. So either get a fan with that or get a Halo. To many decisions!
 

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Premium Member
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27,137 Posts
As already said, experimentation is the way forward.

Keep in mind airflow through a case is like water flowing through container. The maximum flow is bases on which has the lower flow, intake or exhaust. Also keep in mind more fans usually don't make better airflow. Instead they create more turbulence which reduces airflow and mixes all the heated air coming off of things with cool intake air instead of flowing cool air to components while flowing component heated air out of case .. and that is the key; cool air to components .. which requires smooth airflow. So you could probably use less fans with better flow paths and get lower temps. I've found side vents more often then not create airblow rather than airflow. Maybe the 4th post in .Ways to Better Cooling' thread will help explain how to optimize case airflow.
http://www.overclock.net/forum/246-...ing-airflow-cooler-fan-data.html#post22319249
 

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Tetrapyloctomist
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1,708 Posts
My two cents:

- When i see/hear someone mentioning 'exhaust fans' i shake my head. Or rather i used to, because honestly i've read far worse since joining here.
If you have an above average amount of air coming in, warm or at ambients, this way or that way, doesn't matter, at all, then it's gonna be dying to get back out all on its lonesome. You neither need nor benefit, no matter how slightly, from exhaust fans. On the contrary, there's a good chance you're messing things up. And honestly, no offense meant, but.. even a basic, rudimentary, superficial understanding, hell, mere logic, should have told you why. Take them all out. More thinking, less buying, works every time.

- Barring exceptional configurations, any rad whose fans work as an exhaust will have a worse dissipation than if they were set up as intake. I had a look at your case through some random web pics, so based on what you say, i'd have the rear top fan, or the rear two topmost fans as intake; just like on the front side; help my rad (if located at ceiling and with fans set as exhaust) do a bit better job.

- Even though sub-optimal, a dissipator set as exhaust should be preferred, as in such a config there's no hot air recycling (it being another sad trend as of late).

- In a chassis as large as yours (assuming the pics do it justice, cba finding dimensions), you may want to consider static pressure fans everywhere, rather than only for your rad(s). At some distance (fan-to-components) and over, you start caring about having a draft in there, rather than "some" air coming in.

All this for future reference anyway. With that Fractal.. there's only so much you can do, though the above stand regardless.
Hope this helps :)
 

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Premium Member
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27,137 Posts
My two cents:

- When i see/hear someone mentioning 'exhaust fans' i shake my head. Or rather i used to, because honestly i've read far worse since joining here.
If you have an above average amount of air coming in, warm or at ambients, this way or that way, doesn't matter, at all, then it's gonna be dying to get back out all on its lonesome. You neither need nor benefit, no matter how slightly, from exhaust fans. On the contrary, there's a good chance you're messing things up. And honestly, no offense meant, but.. even a basic, rudimentary, superficial understanding, hell, mere logic, should have told you why. Take them all out. More thinking, less buying, works every time.

- Barring exceptional configurations, any rad whose fans work as an exhaust will have a worse dissipation than if they were set up as intake. I had a look at your case through some random web pics, so based on what you say, i'd have the rear top fan, or the rear two topmost fans as intake; just like on the front side; help my rad (if located at ceiling and with fans set as exhaust) do a bit better job.

- Even though sub-optimal, a dissipator set as exhaust should be preferred, as in such a config there's no hot air recycling (it being another sad trend as of late).

- In a chassis as large as yours (assuming the pics do it justice, cba finding dimensions), you may want to consider static pressure fans everywhere, rather than only for your rad(s). At some distance (fan-to-components) and over, you start caring about having a draft in there, rather than "some" air coming in.

All this for future reference anyway. With that Fractal.. there's only so much you can do, though the above stand regardless.
Hope this helps :)
Sorry, but in my opinion our 2 cents worth is a negative 2 cents. You post many thinga that indicate you think you know a lot more then you actually do.

Proper case airflow is not simply having plenty of intake fans or intake and exhaust fans but a combination of many things. It's about having paths / channels of enough cool air going to components to meet their needs and flowing their heated exhaust air on out of case without mixing with the cool air.

If some of the components are air cooled and other components are water cooled all need cool air. Running a 240, 280 or 360 radiator as intake makes it near impossible to keep their heated exhaust airflow from mixing into and heating up the cool air needed by other components.

Depending on where case vents are, sometimes exhaust fans help created a path of air front intake fan to exhaust vent (and fan) and on out of case that without the fan path (flow) would be different and quite possibly result in higher component temps.

So just because we have an above average amount of intake fans and intake air does not mean component are getting cool air.

You are entitled to your opinions, but stop acting like an authority about something it is only too clear you are not. ;)
 

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Tetrapyloctomist
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1,708 Posts
stop acting like an authority about something it is only too clear you are not
I did start by saying "my two cents". For anyone but the severely intellectually challenged, that should be enough to indicate i really was voicing an opinion? Rather than thinking me an 'authority'? Apparently not for you however.
So let me just state that everything i mention above is my opinion and only, just that.

Now as to your reply:
- You mention that both rads and components need cool air! Why that's amazing, no one knew this! Thank you.
- You mention that proper airflow is not merely multiple intake fans. Well again Sherlock, thank you for pointing the obvious. One could have 10 intake fans blowing air straight onto a wall, or bundle of tightly packed cables, or more likely, a corner. Obviously no proper airflow, as no channels. But (and this is why i'm addressing you in such a demeaning manner): 1) not what i'm talking about above now is it, 2) exhaust fans wouldn't help there either, would they, not with no clear path to begin with ^^
- If there is a path/a possibility for one? All it takes is thinking it through, air will let itself out in the end, without assistance (ie exhaust fans). And in the process of doing that, aid in what we care for; currents are formed. Sans aid. Now if you think there can be no path to begin with and it's up to you to "guide" the air, you might want to reconsider PC building in the first place.
And i will accept that not all cases allow for good airflow, but that does not change the base principle.

*Edit: To recap, as i said above, the only "exhaust" fans should be those of your cooler or rad, and only by necessity, so that warm air is not recycled. Stand-alone fans acting as exhaust are either superfluous to begin with, or a demand you've added to your system by not having properly set it up.

Feel free to disagree with me and add an abundance of exhaust fans if you so fancy, but take care of the manner in which you voice your disagreement; especially when the contra-arguments you bring to the table are superficial, self-evident and pointing to a lack of critical thinking. Just my two cents.
 

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Premium Member
Joined
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27,137 Posts
I did start by saying "my two cents". For anyone but the severely intellectually challenged, that should be enough to indicate i really was voicing an opinion? Rather than thinking me an 'authority'? Apparently not for you however.
So let me just state that everything i mention above is my opinion and only, just that.

Now as to your reply:
- You mention that both rads and components need cool air! Why that's amazing, no one knew this! Thank you.
- You mention that proper airflow is not merely multiple intake fans. Well again Sherlock, thank you for pointing the obvious. One could have 10 intake fans blowing air straight onto a wall, or bundle of tightly packed cables, or more likely, a corner. Obviously no proper airflow, as no channels. But (and this is why i'm addressing you in such a demeaning manner): 1) not what i'm talking about above now is it, 2) exhaust fans wouldn't help there either, would they, not with no clear path to begin with ^^
- If there is a path/a possibility for one? All it takes is thinking it through, air will let itself out in the end, without assistance (ie exhaust fans). And in the process of doing that, aid in what we care for; currents are formed. Sans aid. Now if you think there can be no path to begin with and it's up to you to "guide" the air, you might want to reconsider PC building in the first place.
And i will accept that not all cases allow for good airflow, but that does not change the base principle.

*Edit: To recap, as i said above, the only "exhaust" fans should be those of your cooler or rad, and only by necessity, so that warm air is not recycled. Stand-alone fans acting as exhaust are either superfluous to begin with, or a demand you've added to your system by not having properly set it up.

Feel free to disagree with me and add an abundance of exhaust fans if you so fancy, but take care of the manner in which you voice your disagreement; especially when the contra-arguments you bring to the table are superficial, self-evident and pointing to a lack of critical thinking. Just my two cents.
Wow!

Nothing like throwing all your toys out of the pram when others don't agree with you.

Previously you posted
"any rad whose fans work as an exhaust will have a worse dissipation than if they were set up as intake."
Which I interpreted as means radiator fans should be intake, not exhaust and said they usually work better as exhaust .. and that sometimes an exhaust fan helps channel cool airflow where it's needed.

Now you throw a hissy-fit and say
"only "exhaust" fans should be those of your cooler or rad".​
You can't have it both ways. :p

You talk like all you have to do is think how airflow should work / flow and that is what it will do.

Anyone with much experience dealing with airflow in open areas or like in cases without knows that airflow does not always do what we think it should .. in fact as often as not it does something different than what we think .. maybe not much different, maybe quite different.

Like I said before, you post many things that indicate you think you know a lot more then you do. Your advice on how to get proper airflow in a case is not what I (and numerous others here on OCN and elsewhere) have found to be the best way to do things. That is why I replied like I did to your post.
 
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