Questions On Fans (Push/Pull Config)

[LegitD0nuT]

As the title states, I have a couple questions regarding fans in push or pull config. I never really understood the concept (as simple as it sounds) and what it does for my computer depending on which fans are push and which are pull. What exactly does having a fan in push, for instance, mean? "Pushing" air out of my desktop? Would it be best to have my CPU fans as an exhaust, "pushing" hot air out of my computer or "pulling" cool air into the cooling block, which would be "pushed?" out via my rear fan. Should CPU fans be on top of the block the liquid runs through (If using, for example, an H110i) or below it? And in which configuration, pushing air out of my computer or pulling air into my computer? Should the front fans always be "pulling" air into the computer? The entire concept in general confuses me, as stupid as it may sound, and some clarification would be nice Lastly, what exactly is "Push-pull configuration" and the terms used for fans in general.

Thanks for all the help!

 

[Solandri]

The guiding concept behind which direction air should flow is that heat trasfer rate is proportional to temperature differential. So if the air is 20C, the motherboard is 40C and the CPU is 60C, then you want the air to cool the motherboard first, then the CPU. That way the motherboard sees a 40C - 20C = 20C temperature differential. That will heat up the air to (say) 30C. And the CPU will see a 60C - 30C = 30C temperature differential. Then the hot air is exhausted directly out of the case.

If you had fans direct air to the CPU first, then yeah the CPU would be cooled better because it's seeing a 60C - 20C = 40C temp differential. But that would heat the air up to (say) 50C, and now the motherboard is seeing a 40C - 50C = -10C negative differential. Heat is flowing from the air into the motherboard. The motherboard would then have to heat up to 70C to get the same heat transfer as before (20C differential). You don't want that.

So the general idea is outside air over the cooler components first, then over the hottest components just before being vented out of the case.

Edit: A push-pull config is to have one fan bringing air into the case while another directs it out of the case. Generally I don't like these, unless you've got a really convoluted case layout which needs some help directing air to the right places. e.g. If your venting fan is right next to the CPU, but you have a bunch of vent holes right next it, that may set up a circulation around the CPU, while the air in the rest of the case sits stagnant (and the motherboard components heat up). In this case, a second fan on the front of the case pushing air into the case could help overcome this circulation (so would blocking the rear vents).

 

[bailojustin]

Push-pull configurations are when you have a air cooler or a water cooling system with a radiator that you can attach 2 extra fans to the opposing side.

How it works is the rear exhaust fan blows out the back, this leads to a push pull config for the best efficiency on the cpu cooler. how its setup is to have 1 fan on 1 side of the heatsink pushing air through, this air is then not only pushed by fan 1 but pulled out the back of the cpu cooler by fan 2, leading to much better cooling as more airflows over the fins.

This ends up displacing much more air then a regular 1 fan on the side.
These fan systems are usually setup horizontally that way it pushes air in the front of the cooler, pulls it out the back, and your rear exhaust fan pulls any remainder out.

Such as this picture shows the radiator on top blowing upwards, dispelling the heat upwards as hot air rises, this aids in the cooling.
For the CPU cooler like you listed, to have the air pushing through it, then attaching it to the top of a case blowing upwards and out the case, 2 additional fans can then be attached to the radiator or the case, depending on your setup, these fans just aid the CFM, the amount of air moving across the radiator at any given point leading to reduced cooling.

The front fans usually are always intake fans, blowing into the computer. reason being is these fans are generally orientated towards the bottom. We know because of science hot air rises and cool air falls, so your always going to want the best airflow at the top of the case as far as exhaust goes to keep the temps low, and to keep pulling colder air into the case.||

Cases can have a negative or a positive air pressure, this is up to you. Positive means that there is more air being pumped into the case so the inside pressure is greater than that of outside the case. Negative and this is what most pc setups are is there is more air exiting the case then entering, this leads to negative pressure and pulls more dust/air into the case. but results in lower temps as all the hot air is immediately expelled from the case.

You can have the rear exhaust as a intake and the radiators facing downwards while using the front of the case to exhaust the heat.

This is a much less common setup as cooling is not as efficient.

 

[LegitD0nuT]

Push-pull configurations are when you have a air cooler or a water cooling system with a radiator that you can attach 2 extra fans to the opposing side.

How it works is the rear exhaust fan blows out the back, this leads to a push pull config for the best efficiency on the cpu cooler. how its setup is to have 1 fan on 1 side of the heatsink pushing air through, this air is then not only pushed by fan 1 but pulled out the back of the cpu cooler by fan 2, leading to much better cooling as more airflows over the fins.

This ends up displacing much more air then a regular 1 fan on the side.
These fan systems are usually setup horizontally that way it pushes air in the front of the cooler, pulls it out the back, and your rear exhaust fan pulls any remainder out.

Such as this picture shows the radiator on top blowing upwards, dispelling the heat upwards as hot air rises, this aids in the cooling.
For the CPU cooler like you listed, to have the air pushing through it, then attaching it to the top of a case blowing upwards and out the case, 2 additional fans can then be attached to the radiator or the case, depending on your setup, these fans just aid the CFM, the amount of air moving across the radiator at any given point leading to reduced cooling.

The front fans usually are always intake fans, blowing into the computer. reason being is these fans are generally orientated towards the bottom. We know because of science hot air rises and cool air falls, so your always going to want the best airflow at the top of the case as far as exhaust goes to keep the temps low, and to keep pulling colder air into the case.||

Cases can have a negative or a positive air pressure, this is up to you. Positive means that there is more air being pumped into the case so the inside pressure is greater than that of outside the case. Negative and this is what most pc setups are is there is more air exiting the case then entering, this leads to negative pressure and pulls more dust/air into the case. but results in lower temps as all the hot air is immediately expelled from the case.

You can have the rear exhaust as a intake and the radiators facing downwards while using the front of the case to exhaust the heat.

This is a much less common setup as cooling is not as efficient.

Both were great answers and I appreciate the help, but would it be more efficient to put the fans above my radiator, or below my radiator- that are pushing air as an exhaust out of the computer.

 

[bailojustin]

make it so they are pushing air outwards, below the radiator.

 

[LegitD0nuT]

make it so they are pushing air outwards, below the radiator.

So, like this?
http://imgur.com/qdlkK8X

 

[bailojustin]

Damn solandri, first it was a paragraph, now a page lots of edits there lol