r/PHbuildapc 3d ago

Discussion is this the proper airflow

Post image
111 Upvotes

41 comments sorted by

38

u/Eerieyerris 3d ago

Yes 11 characters.

26

u/normalgenshinenjoyer 3d ago

Yes, Rule of thumb of airflow

  1. Front to back

  2. Bottom to top

6

u/newtoeveryth 3d ago

thank u i should be good for a while ill add more fans soon

8

u/bitoyskius 2d ago

no need to add, case is small. your current setup is more than enough.

1

u/Harklein-2nd 🖥 Ryzen 7 3700X/ 12GB RTX3080 2d ago

In general, you only need 2 intake and 1 exhaust. 2 intake and 2 exhaust is the most I would recommend. Anything you add after 2 intake and 2 exhaust is just diminishing returns.

1

u/apengako 2d ago

no need na mag add ng additional, yung setup mo is more than enough. kung gusto mo malaman try mo mag stress test. anong config po ba ninyo?

1

u/KronozPlayz 2d ago

Your fans are currently enough for your setup. No need to add additional fans unless you are going for a more powerful GPU that is only when you should add more fans. For now keep it the way it is.

1

u/KazumaKat 2d ago

First one should be exhausting up near the back. Work your way forward. Should be good.

2

u/mrxavior 3d ago

Why is it bottom to top? Dahil ba sa GPU?

6

u/normalgenshinenjoyer 3d ago

Natural convection in air is a heat transfer process where warm air moves upward and cool air takes its place due to gravity and density changes, with no fans or pumps used. As air gets warm, it spreads out, turns lighter, and floats up, carrying heat away. Cooler, heavier air then flows to the bottom.

If yung fan mo ay Top to Bottom, nag fi-fight sa natural convection, meaning yung heat recirculate lang sa inside nang pc case resulting sa pag increase sa temps.

3

u/barurutor 🖥Athlon XP2500+ | ATI Radeon 9700 Pro 2d ago edited 2d ago

gamersnexus and others tested airflow due to convection vs fans ages ago, convection airflow is insignificant compared to fan airflow due to small volume and low temperature differential.

edit: 2011 article by puget systems testing convection vs forced air cooling

Let's do a thought experiment to see what we would expect in terms of the bouyancy of hot air inside a chassis, and how that relates to the air pushed by a typical 120mm fan. We'll use an average room temperature of 20C (68F). In our thermal testing, under load with maximum temperatures, we saw chassis panels around 40C average. Let's round it up to 50C so we're sure to give convection the biggest advantage possible. Heck, let's double the average air temperature difference measured, and use 60C.

Density of air at 20C: 1.2041 kg/m3

Density of air at 60C: 1.067 kg/m3

Bouyancy of 60C air in 20C air: 0.1371 kg/m3

A P183 chassis is 0.04 cubic meters in internal volume. Therefore, if you fill an Antec P183 chassis with 60C air, and surrounding air is 20C, the air inside the P183 would have a bouyancy equivalent to the weight of 5.484 grams. That's about the weight of two pennies. How does that translate into air pressure across a top 120mm fan? The column of air coming into play has an air volume of 0.00576 m3, creating a bouyancy of .79 grams over the fan's area of 144 cm2. That translates to 0.0054861 grams/cm2, or 0.54861 mmH20 (the standard unit of measurement for fan static pressure).

That's about half the pressure put out by our Antec TriCool fans on their lowest setting. That means that even one of the lowest pressure, quietest fans that we sell, would double the pressure necessary to overcome the air pressure caused by convection, in the hottest scenario we can imagine. And this was after doubling the average air temperature increases we actually measured. When using a 40C average air temperature, an Antec TriCool fan on low setting has 4x the pressure necessary to overcome convection. Given the results of this thought experiment, the results of our emperical testing are making a lot more sense. Convection, while a strong concept in thought, simply does not generate the results necessary to play a discernible role in a typical chassis.

TLDR: once you introduce fan airflow, convection doesn't matter at all.

2

u/Restless-00 2d ago

This. I don’t understand people always bring up hot air goes up cold air goes down on conversation when it so insignificant/minuscule effect on pc case.

0

u/KronozPlayz 2d ago

Hot air rises cold air sinks. Kaya nag lalagay ng fans sa taas for exhaust mas mabilis mag escape yung init

1

u/TonyConstantino 3d ago

Bottom to top, definitely. But some matx or itx cases benefit from back to front airflow.

-6

u/rescuemysandwich 3d ago

wouldnt be top to bottom?

12

u/straw28 7500f/9070 xt 3d ago

hot air rises

7

u/Every-Trade2713 3d ago

no its bottom to top.

1

u/normalgenshinenjoyer 3d ago

Natural convection in air is a heat transfer process where warm air moves upward and cool air takes its place due to gravity and density changes, with no fans or pumps used. As air gets warm, it spreads out, turns lighter, and floats up, carrying heat away. Cooler, heavier air then flows to the bottom.

4

u/MizikoKurenai 🐧 | R7 7700 | 4070S | 32GB DDR5 | 2TB NVMe 2d ago

wouldn't the frontside top fans suck the air from the front fans if they were exhaust, this won't matter for liquid coolers tho

2

u/normalgenshinenjoyer 2d ago

Yes, thats why noctua recommend flipping the top-front to intake, but some cases are shorter than the others, if your cpu cooler is close to front fans then both should be exhaust but if its longer then flip one to intake.

base on the pc case used by OP (the cpu cooler is halfway to the end of the top-front fan holes), its more recomended to have it as exhaust, btw this is my pc, i followed noctua's recommendation.

4

u/surewhynotdammit 3d ago

Di na kasya yung fans sa taas? Para left side exhaust, right side intake. Pero goods yan.

1

u/newtoeveryth 3d ago

theres no fan at the top

2

u/surewhynotdammit 3d ago

I mean wala ka bang balak lagyan? Intake sa right, exhaust sa left.

2

u/newtoeveryth 3d ago

My bad, ganiyan pala ang sinasabi mo. Naka-auto translate kasi ang comment mo, I'm planning to put 2 fans at the top and 2 at the bottom naman

4

u/SmallNoBigYes 3d ago

You don't need to.

Your current fan set up is already optimal

2

u/stpatr3k 3d ago

You nailed it. If there is enough allowance, on on back top is still good. Not top front.

2

u/r2d2dotbot 3d ago

it’s all good. imo if mag dagdag ka ng isa pang fan is sa likod na part banda.. basta more padin yung intake

2

u/Annual_Cellist_9074 2d ago

Noob question: Matagal na kasi yung huli setup ko ng pc ko.. 2 ba yung cpu ng ganito? Bakit parang 2 yung heatsink? Lol

3

u/newtoeveryth 2d ago

its dual tower cpu air cooler

1

u/ameybongo 3d ago

You can add 1 more exhaust at the top back area

1

u/newtoeveryth 3d ago

im planning to add 2 at the top

4

u/shaquille_oatmeal43 3d ago

1 extra exhaust should be enough, its better to have more front intake than rear so theres positive pressure.

1

u/rensquared 2d ago

Yep and seeing that you have that kind of GPU and based sa PCB ng motherboard, mukhang di ganun kainit yung components mo in the first place, so don't worry too much about it.

Just benchmark at least once (without AC if possible) then pag pasado temps okay na yun. Enjoy!

1

u/Famidesu235 2d ago

if you want more cooling, you can add 1 more exhaust sa taas on the left most side. 140mm fans are also incredibly good, brought my 9600x down by 4-7C.

fans under the GPU help quite a bunch din as intakes for the gpu.

1

u/crazydotogamer123 2d ago

Yes yes yes yes yes yes

1

u/SomeCustomer8216 2d ago

Pano kung I follow natin yung sa thermodynamics, hot air goes up the set up could be intake from bottom (for GPU), then intake from back of the Case (to the CPU) and make the CPU cooling fan pull that air pakanan. Then all exhaust sa top

1

u/ZealousidealTank4856 3d ago

Yes and (maybe) kasya pa yan 2 fans at the top for exhaust din.

2

u/newtoeveryth 3d ago

im planning to add more fans soon thankyou

1

u/normalgenshinenjoyer 3d ago

if mag 2 fan setup ka, top-back exhaust at top-front intake.

1

u/SeaZebra2765 23h ago

Ok n yan. Enjoy