Negative, positive or neutral airflow (custom case)

[Chambersofsecret]

I am building my own case for this (specifically a desk pc) and was wondering what would work best for air cooling

[Fasauceome]

16 minutes ago, Chambersofsecret said:

was wondering what would work best for air cooling

pressure doesn't have much bearing on cooling as much as just dust collection. Don't aim for pressure, aim for airflow.

[Chambersofsecret]

5 minutes ago, Fasauceome said:

pressure doesn't have much bearing on cooling as much as just dust collection. Don't aim for pressure, aim for airflow.

Ok well how much airflow would be good 4 intake or 7 output? Vise versa?

[Fasauceome]

1 minute ago, Chambersofsecret said:

Ok well how much airflow would be good 4 intake or 7 output? Vise versa?

really depends on the size of the case and mounting orientation. There's no general rule, outside of the trends set by modern manufacturers, such as two front fans and one rear.

[GalacticRuler]

While there's no strict determination of fan setup, my personal rule of thumb is not to have more than 1 extra fan for a given direction.

[WoodenMarker]

Specs?

[Mattias Edeslatt]

How and where you should place the fans depends on where you have your heat-generating components that you want to keep cool. Intake in front or near those and/or exhaust placed so the airflow is directed over those parts on its way out. For dust management the rule of thumb is to have more airflow in than out to have control of where dust can come in and filter it out as much as possible. But you have to account that as inlets usually are filtered and have a mesh or front panel and outlets often just have a fan-grill the intakes need to be able to have higher pressure and airflow than the outlets to get a positive or balances airflow. A rule of thumb is 2:1-3:1 or 4:2-5:2, the greater number is intake, the lesser number is outtake.

[LogicalDrm]

Ok, lets start from basic terms and what they actually mean.

 

Pressure. How much air is going in vs air going out. This is only to do with dust, and its meaning for cooling performance is commonly misunderstood. For cooling performance more exhaust is actually better as it means that case will remain cooler and cooler air will circulate around components.

 

Airflow. Movement of air around the case. There's no "too much/too little" airflow. Thats not the thing to look at. Its more about at what direction fans will move air and where the components needing to be cooled are located.

 

So it really depends on what kind of design you are going after, where are components needing to be cooled, and where would fans be places. If you look at more standard ATX case design, there's from and bottom fans, mainly cooling drives and GPU (top-most front fan is cooling CPU directly). And rear and top fans for exhaust mainly. In very rare situations would have front-most top fan to be used for intake. As more exhaust is better for performance anyway.

[Chambersofsecret]

9 hours ago, WoodenMarker said:

Specs?

This may change, but should hang around this area 

Ryzen 5 2600

16gb ddr4 3200mhz

ASUS B450

upHere CCF150ARGB

rx 570

[WoodenMarker]

15 hours ago, Chambersofsecret said:

This may change, but should hang around this area 

Ryzen 5 2600

16gb ddr4 3200mhz

ASUS B450
upHere CCF150ARGB

rx 570

Do you have any blueprints of diagrams of the case you're designing? How much clearance would you have for the cooler?

[Chambersofsecret]

8 hours ago, WoodenMarker said:

Do you have any blueprints of diagrams of the case you're designing? How much clearance would you have for the cooler?

No, i wanted to decide on airflow before finishing the case 

[WoodenMarker]

30 minutes ago, Chambersofsecret said:

No, i wanted to decide on airflow before finishing the case 

Aim for the shortest path between fresh air and the cooling component intakes and exhausts. 

So optimally, the graphics card intake and cpu cooler intakes are either well ventilated near the edges of the case or is directly fed by fans. Similar rule for the exhausts. They should exhaust heat in a short path when possible and avoid pulling away fresh air before it's been used. 

A good way to visualize air is to just think of it as water. It works similarly. 

I'd prioritize graphics card cooling since it's more sensitive to temps than the cpu or motherboard. Get that closer to the fresh air intake and just make sure the fans in the system all point airflow in a similar direction.

Positive pressure for reducing dust accumulation is just a matter of filtering your intakes and running intakes at higher rpm than the exhausts. 

[Chambersofsecret]

8 hours ago, WoodenMarker said:

Aim for the shortest path between fresh air and the cooling component intakes and exhausts. 

So optimally, the graphics card intake and cpu cooler intakes are either well ventilated near the edges of the case or is directly fed by fans. Similar rule for the exhausts. They should exhaust heat in a short path when possible and avoid pulling away fresh air before it's been used. 

A good way to visualize air is to just think of it as water. It works similarly. 

I'd prioritize graphics card cooling since it's more sensitive to temps than the cpu or motherboard. Get that closer to the fresh air intake and just make sure the fans in the system all point airflow in a similar direction.

Positive pressure for reducing dust accumulation is just a matter of filtering your intakes and running intakes at higher rpm than the exhausts. 

Wouldnt you have to amp them up a LOT to make up for the lost pressure lost from the filters?

[WoodenMarker]

31 minutes ago, Chambersofsecret said:

Wouldnt you have to amp them up a LOT to make up for the lost pressure lost from the filters?

Filters can easily and dramatically lower airflow. How much of a difference it is depends on the filters and the fans. 

[Chambersofsecret]

27 minutes ago, WoodenMarker said:

Filters can easily and dramatically lower airflow. How much of a difference it is depends on the filters and the fans. 

Ok thanks