[SOLVED] Trying to determine fan placement on/in case to improve airflow

[Lord_Freeholder]

I have a Phanteks Enthoo Pro that can accommodate 8 fans. I came with two 120mm intake fans in the front and one 140mm fan for outtake in the back. I bought four extra fans but they dont fit properly for the screw holes so I plan to mount them with tightly wrapped zip ties. Would an intake fan on the bottom and 2-3 exhaust fans on too be best? Or would an intake fan on the bottom, 2 exhaust fans on top front and middle and one intake fan on the top back, above the GPU make sense? I'm not sure what would be "optimal". Im also thinking of removing the HDD metal barrier thing to improve airflow.

My GPU temps have maxed at 73C and CPU at 63C or so, so I'm not that worried but I figured I would maximize airflow since I have options and bought the extra fans.

Secondly, does it make sense to add some fans outside of the case? For example, intake fans outside the case/filter as opposed the inside the case as normal?

Edit: removed the PSU shroud from the case.
Thank you.

 

[Phaaze88]

Bottom intake fan wouldn't change much, as airflow is being restricted by the psu shroud.
Top-rear exhaust, and depending on the 2nd fan's position over the cpu cooler... you don't want a fan placed too far in front of the cpu cooler, as it would just pull some cool air out of the case before it can feed the cooler.

 

[Lord_Freeholder]

Bottom intake fan wouldn't change much, as airflow is being restricted by the psu shroud.
Top-rear exhaust, and depending on the 2nd fan's position over the cpu cooler... you don't want a fan placed too far in front of the cpu cooler, as it would just pull some cool air out of the case before it can feed the cooler.

Damnit... I should have clarified I removed the PSU shroud. I don't really even understand why it is there.

 

[Karadjgne]

Psu shroud is cosmetic. It's there to hide the rats nest of wiring coming out of the psu, and to hide the hdd/ssd mounted under it. The fan under it is solely for supplying air under the shroud, for the hdd/ssd hidden there. It has no performance benefit to airflow, nor detriment otherwise.

Maxing out fans does not increase airflow, in fact often can be a detriment. Look at the word. Air flow. You are far better off with a single stream of uninterrupted flow, than with massive cfm dumped in at every angle. That creates circulatory patterns, air going sideways.

So optimum airflow in your case is air in front/low corner and out rear/top corner in a single stream.

Removal of the hdd cages can streamline that airflow since the cage blocks the stream, not the air. If the intake fans dump 100cfm inside the case, there's a difference in airflow as that 100cfm just sits there, reliant on the draw from the exhaust fan to suck it up, when the hdd cage is there. Without the cage, that 100cfm has enough pressure to get most of the way to the back of the case by itself, far closer to the exhausts.

With a bottom fan, blowing air in 90° perpendicular to the intake flow, you aren't helping push the air towards the exhausts, but straight up, where it'll mushroom and a good chunk comes right back down the front, to get hit by the intakes again. Big circle going nowhere. Exactly the same thing happens with side mounts, air pushed in every direction, not in 1 direction.

Optimal airflow for that case is 2x 140mm intake in front, 1x 140mm rear and 1x 140mm top-rear with the rest of the ports blocked off. If you want to use the shroud, doesn't hurt either way.

 

[Lord_Freeholder]

Psu shroud is cosmetic. It's there to hide the rats nest of wiring coming out of the psu, and to hide the hdd/ssd mounted under it. The fan under it is solely for supplying air under the shroud, for the hdd/ssd hidden there. It has no performance benefit to airflow, nor detriment otherwise.

Maxing out fans does not increase airflow, in fact often can be a detriment. Look at the word. Air flow. You are far better off with a single stream of uninterrupted flow, than with massive cfm dumped in at every angle. That creates circulatory patterns, air going sideways.

So optimum airflow in your case is air in front/low corner and out rear/top corner in a single stream.

Removal of the hdd cages can streamline that airflow since the cage blocks the stream, not the air. If the intake fans dump 100cfm inside the case, there's a difference in airflow as that 100cfm just sits there, reliant on the draw from the exhaust fan to suck it up, when the hdd cage is there. Without the cage, that 100cfm has enough pressure to get most of the way to the back of the case by itself, far closer to the exhausts.

With a bottom fan, blowing air in 90° perpendicular to the intake flow, you aren't helping push the air towards the exhausts, but straight up, where it'll mushroom and a good chunk comes right back down the front, to get hit by the intakes again. Big circle going nowhere. Exactly the same thing happens with side mounts, air pushed in every direction, not in 1 direction.

Optimal airflow for that case is 2x 140mm intake in front, 1x 140mm rear and 1x 140mm top-rear with the rest of the ports blocked off. If you want to use the shroud, doesn't hurt either way.

That is a stellar reply, wow. I'm book marking this page, thank you so much!

I understand your advice for optimal airflow, I just want to ask one thing. I dont have any HDDs, just one m.2 SSD on the MOBO. What if I I did one 140mm intake fan in the back, two more intakes in the front, and an intake or two on the bottom and all the exhausts on the top? Does that make any sense? Air coming in from the front, back, and bottom and being exhausted from the top?

 

[Karadjgne]

As said, the rear port isn't filtered. 😉

I'm not a fan of intakes sitting high, especially with top exhausts. If you look at that top rear corner, imagine hot air trying to escape. With just an exhaust fan, no worries, sucks all of it right out. Now imagine a fan at rear, set as intake. Right below the exhaust fan. Any air traveling towards that fan just gets blown sideways, and down as air isn't a tight directioned flow, it's a cone. Comes out like a triangle with the fat end farthest from the fan.

Then you also have a high intake at the front, blowing directly at the rear port, like 2 fists in a fist bump. And the rear fan will loose that fight as there's 2x fans pushing high.

It'd be great to use all 4 new fans, but realistically too much of a good thing isn't always a good thing. The gpu would suffer the most, all its heat being shoved right back at it.

 

[Lord_Freeholder]

Tig

As said, the rear port isn't filtered. 😉

I'm not a fan of intakes sitting high, especially with top exhausts. If you look at that top rear corner, imagine hot air trying to escape. With just an exhaust fan, no worries, sucks all of it right out. Now imagine a fan at rear, set as intake. Right below the exhaust fan. Any air traveling towards that fan just gets blown sideways, and down as air isn't a tight directioned flow, it's a cone. Comes out like a triangle with the fat end farthest from the fan.

Then you also have a high intake at the front, blowing directly at the rear port, like 2 fists in a fist bump. And the rear fan will loose that fight as there's 2x fans pushing high.

It'd be great to use all 4 new fans, but realistically too much of a good thing isn't always a good thing. The gpu would suffer the most, all its heat being shoved right back at it.
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Right... those are really fantastic replies. Good imagery. Thank you very much .