Question I bought 2 noctua nf-p12 fans how should i use the floor mount fan?

[namvo222]

So basically I'm planning on using one as exhaust for the rear radiator. For the floor fan in my case, should it be intake or exhaust? My desktop is currently situated at the right side of my table and only a small case of dust is there.

 

[Budge414]

Hi there namvo222!

I would definitely use the floor fan as an intake.

Due to proximity to both the front intake fan/s and graphics card an exhaust wouldn't make sense here.

How many other fans are installed already and where are they in your case?

 

[namvo222]

Hi there namvo222!

I would definitely use the floor fan as an intake.

Due to proximity to both the front intake fan/s and graphics card an exhaust wouldn't make sense here.

How many other fans are installed already and where are they in your case?

Hi there namvo222!

I would definitely use the floor fan as an intake.

Due to proximity to both the front intake fan/s and graphics card an exhaust wouldn't make sense here.

How many other fans are installed already and where are they in your case?

Currently I have a 120mm raidmax case that is in the rear. It's cooling the radiator and it's above the graphic card. That's the only fan currently in my case.

 

[Budge414]

Currently I have a 120mm raidmax case that is in the rear. It's cooling the radiator and it's above the graphic card. That's the only fan currently in my case.

Install one fan in the top slot above the CPU as exhaust, and the other preferably at the front bottom slot as intake if available. If not, the floor slot as intake will do fine.

 

[namvo222]

Install one fan in the top slot above the CPU as exhaust, and the other preferably at the front bottom slot as intake if available. If not, the floor slot as intake will do fine.

Oh yeah I forgot I got a front bottom slot and 2 top slot, (the front bottom fan I'm not sure if it's properly spinning), and the top 2 slot is unoccupied, I believe there is currently no intake fans in my case.

 

[Karadjgne]

Put one of the Noctuas on the radiator. It's pretty much what it was designed for. I'd put both the remaining fans as intakes, either on the front or bottom. You'll get more out of intakes than exhaust because what the radiator fan doesn't use will be cooler by default being from the intakes and will seep out any seams/vents/gaps etc.

 

[Budge414]

Oh yeah I forgot I got a front bottom slot and 2 top slot, (the front bottom fan I'm not sure if it's properly spinning), and the top 2 slot is unoccupied, I believe there is currently no intake fans in my case.

Is the fan that is currently in that position spinning at all? I would replace that front bottom one with a new one and if that fan still works you can use it on the floor slot as an extra intake.

Put one of the Noctuas on the radiator. It's pretty much what it was designed for. I'd put both the remaining fans as intakes, either on the front or bottom. You'll get more out of intakes than exhaust because what the radiator fan doesn't use will be cooler by default being from the intakes and will seep out any seams/vents/gaps etc.

I've always thought positive pressure would work but for me in practice it's always just caused stale/stagnant air inside the case, as when gaming the air inside is no longer cool.

@namvo222 +1 for using the Noctua on the rad.
It's always best to experiment with your case in particular as the ideal configuration can vary, but I've personally had the most success with negative/even pressure (either an even amount of intake/exhaust fans or 1 more exhaust fan). Just my experiences.

 

[Karadjgne]

It's a matter of ability. When a fan blade moves through air, it creates a vacuum behind it, the byproduct of that movement is the exhaust movement of air. The faster the blade moves, the more draw is created. Vacuum draw doesn't reach very far effectively, but is good only for a short distance. Nature abhors a vacuum, so whatever air is easiest and closest will fill it, hopefully including a bunch of heat. This requires air to fill that void. This is where intakes come in, supplying cooler air to replace the warm air vacating through the exhausts.

In a pc, there's 2 sources of cooler air. What the intakes provide and every gap, seam, vent, crack, hole available. In what ppl erroneously call a negative pressure system, there is more vacuum created than intake exhaust can supply. So the exhaust fan vaccum will take air from wherever it can, usually gaps around the fan, top exhaust vents, pcie slots by the gpu. With an aio mounted at rear exhaust, this makes for slightly cooler cpu temps as the immediate air is not heated by gpu/motherboard/case heat, but is direct from the outside, making the radiator more efficient. Case temps will be higher not lower, due to minimal actual airflow allowing case heat to accumulate.

Nothing to do with the amount of fans. Exhaust fans invariably run faster than intakes. The ISA buss sensors controlling the exhaust will be on a warmer area than the sensors for the front fans, so duty cycle is raised. It's very easy to have a single exhaust at higher cfm than 2x intakes, or vice versa.

In a positive pressure system, there's more intake cfm than exhaust, so this will flood the aio rad. Since this air is also picking up gpu/mobo/case heat, it'll make the radiator less efficient, raising cpu temps 1-2°C but overall case temps will be cooler by 1-2°C, as will gpu, drives, VRM's etc.

And the kicker is that this all changes depending on the fans and rpm and ability curves. At low rpm (idle) its very easy to have a negative system that upon raising duty cycle turns to positive or the other way around.

There's a whole lot more that goes into case airflow and thermal dynamics than just having a slightly lower cpu temp.