Intake and exhaust fans sizing advices

Jul 15, 2020
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Hi,

I'm gonna change my current cooling system which is pretty basic for something like:
- 2x140mm intake fans (front of the case);
- a 280mm AIO mounted to exhaust air out of the case (top of the case);
- a 120mm exhaust fan (upper rear of the case).

I'm wondering if the exhaust here is not a little bit oversized compared to the intake. I mean, I've got more exhaust fans than intake ones indeed (3 v 2), but basically 2 fans on the 3 are the AIO ones and I guess they don't perform as well as fans without a radiator to push air through.

What do you think?

Thanks.
 
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What is the model of the case?

What are the models of the fans?

What is your current cooling system? What is the full spec of the system?
Hi Oussebon,

How are you doing?

My case is a Corsair Obsidian 500D.

For the two intake fans, I would go for the Noctua NF-A14 PWM.
The AIO would be the Artic Liquid Freezer II 280, I mean it has good reviews.
For the upper rear exhaust fan, I will reuse my Noctua NF-S12A I already have.

System specs:
- Intel Core i5-9600K (not overclocked);
- 16GB 3000MHz RAM (Vengeance);
- RTX 3080 when it will finally arrive, currently a GTX 1080ti;
- 1xNVMe SSD Samsung 970 EVO Plus;
- 2xSATA SSD but I will keep only one later;
- Corsair RM850+.
 

Zoid

Community Contributor
I think that setup is fine. If you're worried about not having enough intake air, you could go with three 120mm fans on the front panel instead of two 140mm ones. You can also adjust fan speeds so that your exhaust fans are running slower than your intake fans. A decent 280mm AIO shouldn't have to work very hard to cool a 9600K anyway.

Having more exhaust airflow than intake airflow isn't going to hurt anything, your case just might get a little dustier over time due to negative case pressure.
 
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I think that setup is fine. If you're worried about not having enough intake air, you could go with three 120mm fans on the front panel instead of two 140mm ones. You can also adjust fan speeds so that your exhaust fans are running slower than your intake fans. A decent 280mm AIO shouldn't have to work very hard to cool a 9600K anyway.

Having more exhaust airflow than intake airflow isn't going to hurt anything, your case just might get a little dustier over time due to negative case pressure.
Yeah,

I thought about getting 3x120mm intake fans and more particularly the well-known NF-A12x25 PWM, but I'm not convinced the added airflow will really help cooling down the case and might not worth the added noise and price.
Does 3x120mm v 2x140mm really change something cooling-wise?
 
And what is the current cooling setup?

Stock case fans plus what CPU cooler?

i.e. I'm not sure it's worth going out and buying a load of expensive Noctua fans.

Also, is the CPU overclocked? Do you actually need an expensive CPU cooler?
 
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And what is the current cooling setup?

Stock case fans plus what CPU cooler?

i.e. I'm not sure it's worth going out and buying a load of expensive Noctua fans.

Also, is the CPU overclocked? Do you actually need an expensive CPU cooler?
Yeah, two stock case fans and the Noctua. The stock case fans are not bad, but not especially good or silent neither. 2 intake, 1 exhaust.
My CPU cooler is a Corsair H60 (2018 rev) which is... pretty average. It is mounted as an exhaust at the top of the case as well. My CPU is not overclocked.

My biggest concern here is when I'll get my RTX 3080 which is the Asus TUF Gaming one. It's gonna exhaust its hot air directly in the case and I really would like keeping my components reasonably cool and as silent as possible.
 
If you want quiet then the Noctua fans to replace the front intakes are likely to help, though they are expensive and you are paying a high premium for it.

If the GPU is being taxed under load - which of course it should be - then the extent to which you'll benefit may be mitigated by the noise from the GPU's fans.

You could just replace the fan on the CPU cooler with a Noctua NF-A12x25 which would be cheaper than buying one of the best AIOs around for a mid-range CPU that's not even overclocked.

You're getting to a point where you're spending so much on the fans and cooling you could seriously consider switching cases instead/as well if there's something with better airflow.
 
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If you want quiet then the Noctua fans to replace the front intakes are likely to help, though they are expensive and you are paying a high premium for it.

If the GPU is being taxed under load - which of course it should be - then the extent to which you'll benefit may be mitigated by the noise from the GPU's fans.

You could just replace the fan on the CPU cooler with a Noctua NF-A12x25 which would be cheaper than buying one of the best AIOs around for a mid-range CPU that's not even overclocked.

You're getting to a point where you're spending so much on the fans and cooling you could seriously consider switching cases instead/as well if there's something with better airflow.
Is the airflow bad in this case? It's huge, lot of room and lot of possibilities with fan and AIO configurations. I don't think I'm going to switch this case.

I'm waiting for AMD's announcement, but I plan to get a better CPU soon, more of something like an 10700K or Ryzen 3900X equivalent, so I try to find a good cooler able to cool-down those as well, not only my 9600K. Then I'll build another rig with all my spare parts so my father can play FS 2020 as well, huge fan :D
 
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If you want quiet then the Noctua fans to replace the front intakes are likely to help, though they are expensive and you are paying a high premium for it.

If the GPU is being taxed under load - which of course it should be - then the extent to which you'll benefit may be mitigated by the noise from the GPU's fans.

You could just replace the fan on the CPU cooler with a Noctua NF-A12x25 which would be cheaper than buying one of the best AIOs around for a mid-range CPU that's not even overclocked.

You're getting to a point where you're spending so much on the fans and cooling you could seriously consider switching cases instead/as well if there's something with better airflow.
What do you think about Noctua Redux fans? Cheaper, and might be good enough?
 
1) The airflow in the case isn't bad, but then neither is the cooling you have now. You're spending a large amount for what might end up being relatively small gains, to the point where changing to an airflow focused case that will allow fans inside to run slower probably makes a case for itself. So tbh I wouldn't rule out changing the case if spending that much on it.

2) Don't discount the GPU noise. I don't usually do anecdotes but my CPU cooler (single tower air cooler, dual fans) lost a fan that went faulty. I replaced it with a lovely, quiet, NF-A12x15 PWM. It's awesome, so quiet. I can't even hear the CPU cooler under gaming load any more. ... but what I can now hear, now it's not being mixed in with the hum of the CPU cooler is how loud and high pitched my GPU fans are. It's actually a more annoying noise from the system overall.

3) Maybe hold off on purchasing the cooling.

While it's tempting to try to be prepared, it could make more sense to get the RTX 3080 first, and then assess how the system is for noise and temps. It might answer some of your questions for you, which currently can only be answered by speculating, about where you want some fans, what's causing the most noise in the system, etc...

Likewise the CPU cooler. I mean, it's likely it'll do just as good a job with Zen 3 as Zen 2, but there's no harm in letting the product launch and seeing what people's experiences with cooling those CPUs are like first.
 
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1) The airflow in the case isn't bad, but then neither is the cooling you have now. You're spending a large amount for what might end up being relatively small gains, to the point where changing to an airflow focused case that will allow fans inside to run slower probably makes a case for itself. So tbh I wouldn't rule out changing the case if spending that much on it.

2) Don't discount the GPU noise. I don't usually do anecdotes but my CPU cooler (single tower air cooler, dual fans) lost a fan that went faulty. I replaced it with a lovely, quiet, NF-A12x15 PWM. It's awesome, so quiet. I can't even hear the CPU cooler under gaming load any more. ... but what I can now hear, now it's not being mixed in with the hum of the CPU cooler is how loud and high pitched my GPU fans are. It's actually a more annoying noise from the system overall.

3) Maybe hold off on purchasing the cooling.

While it's tempting to try to be prepared, it could make more sense to get the RTX 3080 first, and then assess how the system is for noise and temps. It might answer some of your questions for you, which currently can only be answered by speculating, about where you want some fans, what's causing the most noise in the system, etc...

Likewise the CPU cooler. I mean, it's likely it'll do just as good a job with Zen 3 as Zen 2, but there's no harm in letting the product launch and seeing what people's experiences with cooling those CPUs are like first.
Yeah, you're right. The H60 is garbage but my current CPU is cool enough.

The RTX 3080 under load is gonna be loud enough, around 30 / 40 Dba I think, so might not worth getting an ultra low decibel fan as you have experienced :) But what's more interesting is they have higher static pressure than my current fans. Could be useful for getting air in the case through the small front vents. So, I consider a mix of your options, keeping the H60, keeping my current Noctua but as an exhaust fan, and getting "just" 2x140mm intake fans, maybe Redux for lower prices.
 
I think I'd definitely wait to have the hardware in hand before deciding. You might find the GPU's fans are having to fun so fast to cool it that you desperately do want to maximise airflow (whether in that case or another), in order to cool the card better and so keep its fans quieter. Unless someone's benchmarked the card with your case, system, ambient temps, and usages, and has the same subjective experience of noise as you do, it's mostly guesswork. I'd say let your ears be the final judge :) And buy accordingly.
 
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I think I'd definitely wait to have the hardware in hand before deciding. You might find the GPU's fans are having to fun so fast to cool it that you desperately do want to maximise airflow (whether in that case or another), in order to cool the card better and so keep its fans quieter. Unless someone's benchmarked the card with your case, system, ambient temps, and usages, and has the same subjective experience of noise as you do, it's mostly guesswork. I'd say let your ears be the final judge And buy accordingly.
Thanks, Oussebon.
My 1080ti is so noisy at full-load I dream too much of a very quiet system while gaming like crazy :)
 
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Oh. Well that explains the noise!
Hi Oussebon,

I was pretty surprised to receive my RTX 3080 yesterday. I guess they got some new stock very recently.

So, for the cooling part, I put the Noctua I already had at the top rear of the case to exhaust hot air. It has a very low static pressure but can move a lot of air. Good spot for it I think.
Still got my... hem hem... H60 mounted at the top to exhaust air as well.
Then, I put the two stock fans at the front of the case as intake. They have a higher static pressure than the Noctua, good fit for getting air through the "small" front vents.
Finally, I "only" buy one additional Noctua, the NF-A12x25 PWM. Put it at the bottom front as intake as well so it can blows air directly to RTX 3080 fans.

So far so good, the system is very silent even under load. Nothing in comparison with the mess the 1080ti could do :D

The 3080 climbs to 62°C under load, it's really good.

Might help other people.

I watched airflow optimized case reviews and you're right. For my next build, I'll consider getting one with all the fans coming with it. They are cheaper and better than mine with the 2 extra fans I bought, or actually one, the other one was for an old build case.

Thanks.
 
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Glad you got your hands on a 3080! And that it's an improvement over the last GPU in terms of quality of life as well as horsepower. Great stuff :)

Next up, an eye to Zen 3?

btw what monitor are you using?
 
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Glad you got your hands on a 3080! And that it's an improvement over the last GPU in terms of quality of life as well as horsepower. Great stuff

Next up, an eye to Zen 3?

btw what monitor are you using?
Thank you. It IS a real improvement in terms of quality of life. So f***ing silent. Gaming performances are just like in the reviews. Didn't play much yet, but the little I tried really delivers.

Yep, I'm waiting for Zen 3 announcements and will eventually switch for an AMD motherboard and CPU if performances are great and prices reasonable.

I've got a ROG PG27UQ. I already told you in another post and you were shocked I was playing in 1440p most of the time with my 1080ti on it :) I can FINALLY enjoy my f***ing expensive monitor at its native resolution. It's a real improvement as well and it makes more sense having it now.
 
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Ah right, sorry, I didn't remember the other thread - extra good that you can enjoy the monitor as nature intended!
Yeah, no problem :) I was waiting for next-gen GPUs since I got this monitor. It was a mistake getting it in a first place, but hey, I worked for it and I can enjoy it now.
 

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