Fans - In or Out

nheather · 14 Jan 2020 at 20:34

I have a midi tower case with positions for 5 fans. I have four of them clear in my head but unsure about the fifth.

I have two 120mm fans on the front drawing air INTO the case.

I have one 120mm fan at the back drawing air OUT OF the case.

I have one 140mm fan on the top drawing air OUT OF the case.

Which leaves me with the fifth. This is on the side panel of the case pretty much above the CPU.

Would it be best to configure this to draw air INTO the case onto the CPU cooler or OUT OF the case from the CPU cooler?

Cheers,

Nigel

Dave Burton · 14 Jan 2020 at 20:39

Front/bottom typically intake, top/rear typically outlets, as hot air rises. Gets a bit more complex with rads, but I guess the basic principle is the same...

bremen1874 · 14 Jan 2020 at 20:41

I wouldn't bother with that final fan at all. If you really want it I'd try it both ways, it'd only take a few minutes to flip it around.

Steampunk · 14 Jan 2020 at 20:41

I'd say into the case, but you can always try both ways and see what gives better temps.

spook2575 · 14 Jan 2020 at 21:46

My case also has a slot above the cpu. I didn't bother with a fan there as airflow was good enough already (and have clearance issues with the cpu heatsink)

nheather · 14 Jan 2020 at 21:48

I wouldn’t have bothered but I have a glut of fans, bought a box of five because it was cheaper than buying four singles. Schoolboy error because I didn’t realise one of the fans needed to be 140mm, which I then had to buy separately.

Would have been cheaper to buy 3x 120mm and 1x 140mm but mustn’t cry over spilt milk - but fitting it will make me feel better as I will only have one left over not two.

I will check what direction the CPU fan spins and harmonise with that.

Cheers,

Nigel

doyll · 15 Jan 2020 at 20:38

As a couple others said, don't bother. It's more than likely a side fan would disrupt case airflow more than help it.

EsaT · 15 Jan 2020 at 21:26

Side panel fan blowing toward CPU could work quite nicely with down blowing coolers.
But with standard for long time tower heatsinks airflow would be mess at best.

nheather said:
I have four of them clear in my head...

Aren't those fans supposed to be in PC case?
Sorry... couldn't resists.

drakulton · 15 Jan 2020 at 23:28

What kind of CPU cooler do you have?

DoneADougalOnSofa · 15 Jan 2020 at 23:33

Just counted mine... Ten. 8 120s in, 2 140s out.

Ouch.

Drumroll · 16 Jan 2020 at 08:58

No real benefit for the CPU I guess, but may help the GPU and M.2, RAM and MOSFET.
Just carefull as fans attached to side panels tends to cause vibration.

Steampunk · 16 Jan 2020 at 09:54

You could just leave the fan off and leave it as a vent. You may find if you have temp controlled fans that a vent in the side of the case will behave differently (ie as an input or an output) depending on how fast your other fans are running. Just put a dust filter on it.

alec · 16 Jan 2020 at 10:31

If you have top-down CPU cooler or waterblock put a fan blowing IN

Terminal_Boy · 16 Jan 2020 at 10:59

Spend 5 minutes making a sketch of your case and the airflow direction from each fan and the CPU cooler. You shouldn’t have fans opposing each other and make sure that the entire case has good circulation.

Does the cooling system for your graphics card exhaust hot air inside the case or out via the rear panel?

doyll · 17 Jan 2020 at 23:49

What EsaT and others are saying about just filling holes with fans. Usually results in lots of air blow and not good air flow.

You might find link below to basic guilde of how airflow works and how to optimize case airflow of interest.
https://forums.overclockers.co.uk/t...-i-put-my-temp-sensor.18564223/#post-26159770