Re: need help with a Micro-atx gaming build
The HS fans pulls air through the fins and blows it in the direction of the case fan which is blowing out the back. So yeah it's a push pull setup. In the bios I have the rear exhaust fan linked to the HS fan controller. When the HS fan revs up so does the rear fan. The two top fans run on motherboard sensors and rev up and down as the case temps vary.
I've run many tests over the years and find blowing air into the fins doesn't work so well. Take my CM 212 evo for example. The fins are too close together to force air in to the gaps. You have a fan trying to push air in at a high rate and because you can only force so much air in to that gap, you wind up with a high pressure boundary at the openings to the gaps between the fins.
Now if you take that same fan and turn it around so it's sucking air through the fins, you create a low pressure area in between the fins. Nature doesn't like low pressure or vacuums for that matter. So the air moves in to the low pressure area. As the face of the fan is the lowest point of pressure the blades just scoop it up and move it on along.
The case fan is turned so it's blowing out of the case, like it should be. Since both the case fan and the HS fan are on the same controller in the bios, the air coming off the HS fan is ushered on out the back.
I run my case with air coming in the 240mm tall by 120mm wide filtered intake. It goes through the HD cage and on in to the main area. The two top fans take care of the case heat while the HS / back fan take care of the CPU heat. It's a low pressure cabinet so it's really efficient.