How much airflow is too much airflow?

[StyleandAplomb]

I am building a new PC, and part of my planning involves thinking a lot about maximizing airflow through the system. The case I am building in is a Phanteks Enthoo Pro with an Intel 8700k cpu, Noctua NH-D15 cpu cooler, and a Gigabyte GTX 1080 gpu. The Phanteks case comes stock with one Phanteks PH-F200SP_BK fan rated at 110.1 CFM installed as a front intake, and one Phanteks PH-F140SP_BK fan rated at 82.1 CFM installed in the rear as exhaust. While I am somewhat confident that this setup is plenty fine on it's own, I would much rather have a system which replaces the total case air volume (as far as I can tell the Enthoo Pro has an internal case volume of 2.44 cubic feet) and maintains a higher internal pressure than those two fans alone can provide. To that end, my current plan has me installing two 140mm Noctua NF-A14 IndustrialPPC-2000 fans, each rated at 107.4 CFM, as intake, one more Noctua NF-A14 IndustrialPPC-2000 as rear exhaust, and moving the stock Phanteks PH-F140SP_BK to a top exhaust behind the cpu cooler. By my math, that's 218.8 CFM (3.65 cubic feet per second) intake and 189.5 CFM (3.16 cubic feet per second) in exhaust, keeping positive pressure. All these fans also have 4-pin connectors, so setting a custom fan curve will be one of the first things I do. But looking at the numbers I'm a little concerned that it's maybe too much air moving through the PC at any one given time, I'm not married to this setup and would like to hear some of your thoughts.

[jiyeon]

There's no such thing as too much airflow, but if you're not optimising the air pressure - positive, neutral, negative etc - that's where air flow goes wrong.

[StyleandAplomb]

1 minute ago, seoz said:

There's no such thing as too much airflow, but if you're not optimising the air pressure - positive, neutral, negative etc - that's where air flow goes wrong.

Well I don't think pressure is going to be a huge issue given the CFM disparity between intake and exhaust. My worry is that, given the sheer volume of the air I'm going to be moving with these fans, I'll end up recirculating warm air around the case or causing big pockets of turbulence. For whatever it's worth I am also leaning heavily on the idea that I can modify the psu shroud in the case and remove as many HDD cages as possible, up to and including modifying the cage stacks, so allow totally unimpeded airflow through the front of the case.

[FastRDust]

Well when your components rip-off the boards, that is where i would draw the line.

if anything else I would say that noise would be a limit you'll run into earlier than air flow.

[StyleandAplomb]

1 minute ago, FastRDust said:

Well when your components rip-off the boards, that is where i would draw the line.

if anything else I would say that noise would be a limit you'll run into earlier than air flow.

Yeah I know those Noctua fans are not exactly silent running, which is why it was so important that they be pwm. I think I might have to buy a pwm Y splitter though since my motherboard technically has 6 4-pin fan headers but one of them is in a stupid place. I hope I'm not running this PC under heavy load all the time, though.

[RAM555789]

There high pressure fans, and do great in contained spaces like CPU cases, or when attached to a heat sink. (which might be fun to see how low you can get your temps).

[Kenji the Uke]

 

[WoodenMarker]

Effective cfm is lowered due to obstructions like mesh, filters, and other structures. The front doubles up on a mesh and filter so it'll likely inhibit airflow more than the exhausts. 

Why do you want more positive pressure? The only benefit from it is preventing dust from entering unfiltered openings. The stock case fans should already be enough for that.

[StyleandAplomb]

5 hours ago, Kenji the Uke said:

 

I've watched that video, and while I appreciate that in the end it's not an earth-shattering difference either way, I am unfortunately a chronic worrywart and overthinker. And since it doesn't make much of a real world difference past a certain point, if having the setup I described above makes me feel better then it should be fine, right?

 

3 hours ago, WoodenMarker said:

Effective cfm is lowered due to obstructions like mesh, filters, and other structures. The front doubles up on a mesh and filter so it'll likely inhibit airflow more than the exhausts. 

Why do you want more positive pressure? The only benefit from it is preventing dust from entering unfiltered openings. The stock case fans should already be enough for that.

The fans I am installing in the front are also very high static pressure (4.18mmH2O), so the mesh filters should not cause any problems to my knowledge

Protecting my computer from junk exactly why positive pressure is very important to me. I live in an environment with a lot of dust, and more concerning, a lot of pet hair. With two dogs and a cat, without maintaining good positive pressure the inside of my PC would get gunked up in no time flat. 

[Kenji the Uke]

Honestly, yeah. Build what you want :3 Hour the one who will be using it, so you build your dream pc with what you got man. You cant go wrong

[LogicalDrm]

On 10/16/2018 at 1:51 PM, StyleandAplomb said:

Well I don't think pressure is going to be a huge issue given the CFM disparity between intake and exhaust. My worry is that, given the sheer volume of the air I'm going to be moving with these fans, I'll end up recirculating warm air around the case or causing big pockets of turbulence. For whatever it's worth I am also leaning heavily on the idea that I can modify the psu shroud in the case and remove as many HDD cages as possible, up to and including modifying the cage stacks, so allow totally unimpeded airflow through the front of the case.

 

Is the worry about circulation for temps or something else? More airflow = lower temps. As some of obscure cooling videos have proven:

Spoiler

 

 

On 10/16/2018 at 2:07 PM, StyleandAplomb said:

Yeah I know those Noctua fans are not exactly silent running, which is why it was so important that they be pwm. I think I might have to buy a pwm Y splitter though since my motherboard technically has 6 4-pin fan headers but one of them is in a stupid place. I hope I'm not running this PC under heavy load all the time, though.

So you are going to miniscule point of high airflow fans by reducing their airflow? You will get dust inside the case anyway. Even if you would be running it 24/7. No filter is perfect.

[geo3]

On 10/16/2018 at 4:47 AM, seoz said:

There's no such thing as too much airflow,

If you install an EDF instead of a normal computer fan and components are being ripped out of their sockets I'd say that's too much airflow.