About the Phantom 820's top-front fan

[Phaaze88]

So, in NZXT's own manual, this case is intended for negative pressure with both top fans set for exhaust. But actually looking at the interior of the case from the side, the top-front fan doesn't appear to serve any real purpose, aside from the whole +/- pressure thing, which I've found isn't as important as actual airflow. The interior is going to get dirty regardless of +/- pressure, so just do maintenance regularly.

Should I leave it as exhaust anyway? Or turned off perhaps?
Or maybe even as intake, at least that way, it could feed more air to my cpu cooler(D-15s, dual fan, push mode)?

 

[Aeacus]

Since hot air rises, case's airflow rule of thumb is: front & bottom - intake; top & rear - exhaust.

You can turn one of your two top exhaust fans off if you like. But flipping it and setting it as intake would work against natural convection.

 

[Phaaze88]

Since hot air rises, case's airflow rule of thumb is: front & bottom - intake; top & rear - exhaust.

You can turn one of your two top exhaust fans off if you like. But flipping it and setting it as intake would work against natural convection.

So in turn, it would actually increase cpu temps?
I believed it would turn out differently due to it's position over the mobo(atx), which it really isn't - looking inside the case, it's actually above and to the right of the mobo.
I'll leave them both as exhaust then.

 

[Aeacus]

Also, having 2x different orientation fans side-by-side creates airflow loop as well, making any cooling actually worse. Image to explain it:

Oh, you don't have to create negative pressure inside your PC case. As long as you run your intake fans higher speeds than exhaust fans, you'd get neutral or even positive pressure.

 

[Phaaze88]

That's what I needed to see!
But the pressure situation isn't all that important, as dust is still going to get inside. Just someone running a negative pressure setup may need to clean it more frequently.

Is there an app or controller I can use for my case fans? I have a profile set up for my cpu cooler in the bios, but I can't seem to do it there for the case fans. There is however, a few buttons at the top of this case that sets fan speeds, but aside from the highest and lowest setting(just simply pressing the -/+ as far as they'll go), I can't see rpms at all. I'd like to be able to set a fan profile for these as well.

 

[Aeacus]

While it's true that with negative pressure, you can get more dust in your PC than with positive pressure, negative pressure is also best at cooling your PC. Also, depending on how you've set up your airflow system, case used and if you use custom aftermarket filters, you may get very little dust in your PC even when running negative pressure.

For example, my Skylake and Haswell builds have negative pressure since in both PCs, i have:
2x 140mm front intake
1x 120mm bottom intake
3x 140mm top exhaust
1x 140mm rear exhaust
(full specs with pics in my sig)

But since i've covered all grilles of my cases with high-grade Demciflex filters, i can run my systems months before internal cleaning is required. Also, internal dust is very fine and tiny. Drawback is that i need to clean my dust filters weekly but since they are external and held place with magnets, taking them off, cleaning them and putting them back is very easy.
Demciflex: https://www.demcifilter.com/why-demciflex

Which MoBo do you have? Also, are your case fans the stock ones that came with Phantom 820 or have you replaced them? And are the case fans 3-pin or 4-pin?

Since so far, your airflow setup seems to be stock. Your case has built-in fan controller with 4x channels and 2-3 steps. If you want to see the RPM and control your fans via BIOS or 3rd party software, then you need to unplug them from case's built-in fan controller and plug them directly into your MoBo.

 

[Phaaze88]

Mobo is Asus x299 Prime Deluxe.
The case fans aren't exactly stock, but I've occupied all slots with NZXT's own RF series fans, 200 and 140mm. The fans are 3-pin, not 4, like the Noctua's are, and so, I can't plug them into the board directly, as it only supports 4-pin connections.
Should I look into replacing them with 4-pin fans? I was already considering doing so, plus my mobo came with a fan controller extension card.

 

[Aeacus]

You can plug 3-pin fan into MoBo's 4-pin fan header just fine and vice-versa,
image:

With fans plugged directly to your MoBo, you can control them within BIOS and also see the fan RPMs.

Out of the 8x fan headers on your MoBo, you can use 6x of them for your case fans. 5x if CPU_OPT is also taken with NH-D15s. Or you can double the fan support on MoBo by using Y-splitters and connect 2x fans on single MoBo fan header.
Y-splitter at amazon, 2x in the box: https://www.amazon.com/Noctua-NA-SYC1-Accessory-4-pin-Y-Cables/dp/B00KG8K5CY

If you use the included fan extension card then any fan plugged into there can be controlled only by Asus Fan Xpert 3 & 4.

 

[Phaaze88]

Now that helps a ton! I'll get started on that tomorrow, as I was already planning to clean out my case.
Thanks for your time!