Show us your fan/air flow layout

[80-watt Hamster]

1) 9700K/RTX 3050/Antec Sonata SOLO: 2x92 in, 1x120 out
I love this case, but it's pretty old as the hills, so airflow's not the greatest, but the thermal load is low enough that it can run WCG and F@H 24/7 without the fans too loud.

2) 10700K/RX 5600 XT/RX 470/Fractal Define 7 Compact: 2x140 in, 1x120 out
D7C's airflow setup is almost identical to the SOLO if not using the vented top panel, meaning it's not terribly efficient as an airflow case. (Though it's a really good case overall.) Fans need to work pretty hard to keep temps down for 24/7 crunching.

3) 11700K/GTX 1070 ti/RTX 2060S/Fractal Torrent Compact: 2x180 in
This is the stock setup for the TC. I did get a 3C drop on GPU temps blocking off the bottom intake grille. Both GPUs are running with reduced power limits to leave some PSU headroom, so I don't know what I'd be getting for temps if they were running full tilt. Also a 24/7 cruncher.

4) 5600G/some Ultra ATX thing: 1x120 in (or out, I can't quite remember)
It's a 5600G that exclusively runs a Valheim server, it barely needs cooling.

5) Xeon E5450/HD 5450/Superpower Zephyr: 1x80 in, 1x80 out
All it does is serve files. It could probably make do with only one of those fans.

EDIT: All of these are front-to-rear.

You may sense a theme in the above. Micro Center has, or at least had, a marked tendency to firesale Intel CPUs on generation shift. It's hard to say no to a $200 (or less!) i7.

 

[Vayra86]

General rule, ALWAYS more outtake than intake, now 2 factors here, the fan dimensions and rotation/flow regarding air flow pressure/dust accumulation inside the cabinet.
The more intake flow/pressure the more accumulated heat inside and dust, what we want is a nice flow to take those out and an acceptable fan noise.
And please avoid those damm glass panels if the machine is a power horse and silence is not primary concern.

Wha... thats like the polar opposite of reality. Positive pressure is a low dust scenario. Not negative

 

[FoulOnWhite]

My temps are great and i think it is slightly positive as i think that is best for less dust, but inside it is quite dusty, ao not sure what to do now.

I have filters on the front and side fans which are in, the rad and rear are out.

 

[oxrufiioxo]

Wha... thats like the polar opposite of reality. Positive pressure is a low dust scenario. Not negative

Yeah more exhaust leads to air being sucked in from every hole it can be drawn in from.

Depending on case though it can lead to better temperatures but never less dust assuming all intakes are properly dust filtered in a positive airflow scenario.

Temps in relation to positive or negative air pressure is very case dependent it can also vary depend on if an aio/air cooler/open loop is being used.

I always test all varientions with a case and just go with works best for that specific case and sometimes even fans used can make a difference.

My temps are great and i think it is slightly positive as i think that is best for less dust, but inside it is quite dusty, ao not sure what to do now.

I have filters on the front and side fans which are in, the rad and rear are out.
View attachment 320731

You'll never completely eliminate dust and depending on environment the pc sits in will be less or more of an issue. A quick spray out once a month is about the best you can do to keep it in check regardless of a positive/negative airflow setup.

 

[phanbuey]

There's a pocket of space that let's the 140MM push the heat out. Works very quietly. Also a tiny bit of positive pressure.

 

[Chrispy_]

I'm not home to take photos but I have a Corsair 4000D with 3x120 front intakes, exhausting via a thick 280mm radiator in the roof a slim 120 radiator in the back. I maintain positive pressure with fan curves keeping the front fans spinning a little faster than the exhaust, and of course the radiators act as airflow resistance to the exhaust.

The HTPC in the living room is in a Silverstone GD09 which sucks fresh air from either side and spits it out the back with a pair of 80mm fans and lots of venting in the roof and unused expansion slots are all ventilated. 3x120 intakes mean a lot of positive pressure as I'm using T30's.

 

[FoulOnWhite]

I'll try adjusting the fans with the OCTO controller to have the fronts run slightly faster in maybe for a bit more positive.

 

[meatwar]

Wha... thats like the polar opposite of reality. Positive pressure is a low dust scenario. Not negative

Correct, Pos Pressure not Negative now... there's still some percentage of users who can't decode what i wrote...not just reading, that's ok no offense taken.

You take good care of your rig now, cheers.

 

[Chrispy_]

I'll try adjusting the fans with the OCTO controller to have the fronts run slightly faster in maybe for a bit more positive.

With 6 intakes and 3 of your four exhausts having to push through a thick radiator, I'm sure you already have positive pressure. I would look more carefully at the filters and the type of dust you're seeing inside. If they're all very unrestrictive open mesh filters then they'll do nothing to stop the fine dust.

The best filters are also the most restrictive, so if you don't want to replace for finer filters, the alternative option is to vacuum your room much more frequently to try and keep the amount of dust in the room lower. I have a roomba that cleans daily, so my hardwood floors are always spotless and there's very little dust, but I deal with office PCs all day every day where there's carpet and a lot of foot traffic to make vast quantities of dust.

Correct, Pos Pressure not Negative now... there's still some percentage of users who can't decode what i wrote...not just reading, that's ok no offense taken.

I can decode what you wrote just fine, this post is just factually wrong.

 

[Vayra86]

Correct, Pos Pressure not Negative now... there's still some percentage of users who can't decode what i wrote...not just reading, that's ok no offense taken.
View attachment 320750
You take good care of your rig now, cheers.

No you just switched positive and negative around, you literally said you want more outtake than intake, which is negative pressure, which is high dust build up. Its not rocket science.

Cheers. No offense taken either for the wrong accusation and your inability to reflect on what you wrote.

On the off chance you just don't get it, here's the explanation based on your picture:

In the above scenario, the PC case is the hallway.
Air is everywhere, Its also in the room. This picture assumes there is NO air in the room, and therefore, air flows into the room. Whoever thought this up is an absolute fool. It doesn't say 'vacuum pressurized room'. Because in our earthly environment, if we want NO AIR in any space, we need to work on it. Hard. The room must be 100% sealed, to begin with. If that door's open... the room and air pressure will be equal in a split second.

So, assuming there is ALREADY air in the room, which makes the room similar to your case... The above positive room pressure scenario is applicable. But those arrows show the 'outtake'. Now, what happens when that room does not receive enough new air to replace the old (which is: more outtake than intake for air)? You get the opposite effect: you're sucking air in, because the air pressure in the room and the hallway will always be equalized, since we don't live in a vacuum or, space. And since you have no control over where the sucking in happens, (likely not mostly through filtered vents, because that's an obstruction compared to open holes), you suck in lots and lots of dust.

You can't argue with physics or thermodynamics, sorry.

 

[Chrispy_]

I'm not even sure why we're trying to salvage a "room and hallway example" in the first place!

A PC case is a continuously-balanced open system with moving air at all times, not an imbalanced, closed system represented by two rooms at different air pressures and an instantaneous one-off equalisation of air pressure when a door is opened; It's a terrible example that doesn't match the system or the state, and to add to the confusion, the "room" in the example doesn't represent the "room" a PC case is in; That's as counterintuitive as you can get.

The idea of positive air pressure for dust control is super simple to get your head around if you look at an easy example of a closed box with negative air pressure instead; a vacuum cleaner. It has a box (or cylinder) at reduced air pressure, which sucks all the dusty crap from outside the box, and collects it in the box.

Do you want the inside of your PC to look like the dirt-collection box of a vacuum cleaner? No!
So don't set up your fans like a vacuum cleaner with a surplus of exhaust fans sucking all the crap from outside through every gap in your case instead of through your intake fan dust filters.

 

[LabRat 891]

I'm not even sure why we're trying to salvage a "room and hallway example" in the first place!

A PC case is a continuously-balanced open system with moving air at all times, not an imbalanced, closed system represented by two rooms at different air pressures and an instantaneous one-off equalisation of air pressure when a door is opened; It's a terrible example that doesn't match the system or the state, and to add to the confusion, the "room" in the example doesn't represent the "room" a PC case is in; That's as counterintuitive as you can get.

The idea of positive air pressure for dust control is super simple to get your head around if you look at an easy example of a closed box with negative air pressure instead; a vacuum cleaner. It has a box (or cylinder) at reduced air pressure, which sucks all the dusty crap from outside the box, and collects it in the box.

Do you want the inside of your PC to look like the dirt-collection box of a vacuum cleaner? No!
So don't set up your fans like a vacuum cleaner with a surplus of exhaust fans sucking all the crap from outside through every gap in your case instead of through your intake fan dust filters.

'Used to disagree. Then, I tried out positive pressure myself.
Now, I'm a believer.

There's still some 'point' to negative pressure cases but, the dust is just too much hassle.

My next case will probably have single/few well-controlled, high-pressure, and filtered intake fan(s); with 'silent' exhaust fans.

 

[Chrispy_]

'Used to disagree. Then, I tried out positive pressure myself.
Now, I'm a believer.

There's still some 'point' to negative pressure cases but, the dust is just too much hassle.

My next case will probably have single/few well-controlled, high-pressure, and filtered intake fan(s); with 'silent' exhaust fans.

Negative air pressure in a PC case still works fine for cooling, it's just that you can't control where the intake comes from. Unless your entire case is made out of dust filter, you're going to get more dust.

Some people argue the merits of positive/negative pressure in a PC case based on totally-sound physics, but not enough understanding. Yes, it's 100% true that low pressure air flows faster than high pressure air in many circumstances, and it's also true that high pressure air has a greater thermal mass and can transfer more energy away from heatsinks for any given flow rate. In reality the air pressure in your case is going to be somewhere between 0.9998 atmospheres, and 1.0002 atmospheres no matter how you arrange your fans. The difference in air pressure is going to be negligible because your case isn't an airtight vessel, air will flow from high-pressure to low-pressure areas following the path of least resistance. Any benefits people think might apply from higher-density high-pressure air, or faster-flowing low-pressure air are irrelevant to a PC case because even measuring the tiny difference in air pressure is going to be difficult. The difference in flow rate or thermal mass is going to be an even smaller fraction of that already tiny and negligible pressure difference.

Realistically, when we talk about positive pressure and negative pressure for PC cooling, we're only really referring to the balance of airflow between intake fans and exhaust fans. Any imbalance in this fan airflow determines the direction of the (nearly) equal and opposite airflow from atmospheric pressure in all the places where the fans aren't.

My next case will probably have single/few well-controlled, high-pressure, and filtered intake fan(s); with 'silent' exhaust fans.

The best filtration happens at low airflow, where the electrostatic charges that make dust stick to everything (like dust filters) isn't overwhelmed by the strength of the air currents from a high flow rate.

For an ideal dust-filter in a PC case, this means you want as much filter surface area as possible and you want the fan to be recessed away from the filter to allow air from the whole filter to reach the fan rotor. In most other applications of filters, you see these concertinas of folded filter to increase the surface area. Doubling the surface area halves the speed that air passes through the filter; it's directly proportional.

I have no need for advanced dust filtration at home, but if I was being asked as an engineer to design a better-filtered case, I would find a case with a relatively large 420mm front panel filter with nice fine mesh and enough room to build/3D-print a duct down to a much smaller 240/280mm fan arrangement. Although a concertina-style filter would be the most effective for filtration and the lowest resistance for the fans, they're a bastard to clean, so I'd settle for the flat, plastic mesh type we have in PCs as long as there was space for a duct to ensure that the smaller fan(s) could effectively use the whole filter.

 

[FoulOnWhite]

Maybe a case that is a proper boxe with the only openings being the fan openings instead of all the slots openings etc, would work better for positive pressure setup, and actually make the case positive pressured.

That's why i wondered in my op if taping up as many non fan openings as possible would make any difference.

 

[80-watt Hamster]

Maybe a case that is a proper boxe with the only openings being the fan openings instead of all the slots openings etc, would work better for positive pressure setup, and actually make the case positive pressured.

That's why i wondered in my op if taping up as many non fan openings as possible would make any difference.

It can for certain case designs.

3) 11700K/GTX 1070 ti/RTX 2060S/Fractal Torrent Compact: 2x180 in
This is the stock setup for the TC. I did get a 3C drop on GPU temps blocking off the bottom intake grille. Both GPUs are running with reduced power limits to leave some PSU headroom, so I don't know what I'd be getting for temps if they were running full tilt. Also a 24/7 cruncher.

With only the two 180mm intake fans, my TC is 100% positive pressure, though I suppose the PSU technically counts as an exhaust. The Torrent series was designed to be run wind-tunnel style, though; I suspect most cases won't see significant gains from sealing up unused vents.

 

[de.das.dude]

240mm rad is in push pull.

 

[maxfly]

Backup rig, Corsair 5000d Airflow- front 360 rad, w/3x120 Corsair ml120pro rgb, inlet. Top 240 rad w/2x120 Noctua ippc 2000, exhaust. 1x120 Noctua ippc 2000 exhaust. Very little dust, ever. Solid temps and quiet, until 240 fans are uncorked. Load temps are excellent...but annoyingly loud.

Main rig, Thermaltake x71- front 420 rad, w/3x140 Noctua ippc 2000, inlet. Top 360 rad, 3x120 Noctua ippc 2000, exhaust. 1x140 Noctua ippc 2000, exhaust. Bottom chamber 360 rad, 3x120 Noctua ippc 2000, inlet.
Dusty AF but ch ch chilly.

 

[N/A]

Wouldn't it be better to have a fog machine instead of arrows. I'm not sure the airflow is exactly what you think it is. It could take you by surprise.

 

[Beginner Macro Device]

Spoiler: Nothing all too fancy

 

[de.das.dude]

Wouldn't it be better to have a fog machine instead of arrows. I'm not sure the airflow is exactly what you think it is. It could take you by surprise.

i verified it with a smoke test.

Spoiler: Nothing all too fancy

View attachment 320815

you dont have any intakes?

 

[Beginner Macro Device]

you dont have any intakes?

Who needs intakes when it's 40F inside?

 

[de.das.dude]

Who needs intakes when it's 40F inside?

what the fuck. no heating?

do you know of this game called cities skylines? its a good room heater.

 

[Beginner Macro Device]

no heating?

I'm just kidding. My hottest component, a GPU, runs ~100C on the hotspot with the worst thermal paste possible at the maximum overclock. I'm usually about 30C away from danger. I don't realistically need extra airflow. CPU is in low 60s, SSDs are cool, RAM is low clocked and thus, also cool. PSU? I use it below 40%, it can't be bothered.

 

[Chrispy_]

Maybe a case that is a proper boxe with the only openings being the fan openings instead of all the slots openings etc, would work better for positive pressure setup, and actually make the case positive pressured.

That's why i wondered in my op if taping up as many non fan openings as possible would make any difference.

I did the tape thing a long time ago and it didn't make much difference, though it did actually make it very slightly worse.

You can't make a PC case airtight unless you go to town with silicone sealant, which is obviously a disaster for later access/maintenance. In terms of cooling, letting heat escape is more important than controlling exactly where the airflow is going, so all those gaps and cracks between case panels leaking hot air is actually a net benefit.

Priorities, in order, should be:

1. Exhaust airflow as close to the heat sources as possible
2. Filtered intakes to cut down the bulk of the dust ingress
3. A surplus of intake fan airflow to ensure that filtered air is pushing out through gaps in the case, and preventing further dust ingress.
4. covered or filtered top panel to stop dust from falling down inside the case when the fans aren't on to mitigate this.

 

[QuietBob]

Not much to describe, a single 140 mm fan as an intake, with a single 120 mm exhaust:

The case has a filtered full mesh front. Only the top 5.25" bay is occupied. Unfortunately, the upper 3.5" cage is riveted in place and can't be easily removed.
The front fan is an Arctic Bionix P140 - 1,950 rpm, 77.6 cfm, 2.85 mm H20, with an additional fine mesh metal filter, idling at ~1,200 rpm.
The rear fan is an NB-eLoop B12-4 - 2,400 rpm, 88.5 cfm, 2.74 mm H20, with the case fan grille cut out for unrestricted exhaust, idling at ~1,300 rpm.
These are my current idle temps in a 23 C room: