Which way is the air flowing, how should it?

By NeonShadow ยท 9 replies
Nov 27, 2004
  1. I recently built a new system. My first time and so far things are grand. I got a question on fans that kinda got me thinking for quite a while. When I was screwing on the fans to the side and back of the case, I was woundering which way the air is going? Is it blowing air in or out? Is it even curculating?

    The front of my case tells the temp. of inside. It reads 82.0 F. I was thinking my fans are probably in right. But I would like to make sure.

    How would I go about seeing which way the air is going, and how should circulation go?

    Thank you.
  2. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    Intake fans at the front of the PC should bring cool inside the case. Your CPU fan typically will be blowing air towards the heatsink unless stated otherwise (for example Alpha Heatsink/Fan combos are meant to pull air from the bottom of the heatsink, away from the CPU). The exhaust fans at the back of the case should be expelling the hot air outside of the case.

    PS. Welcome to TechSpot. Hope you enjoy your stay.:wave:
  3. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Your case temp looks fine.

    How many fans do you have in that case?

    If everthing seems to be running ok I wouldn`t worry to much.

    I have two case fans one on the side and one on the rear after experimenting a little I found that having the side fan blowing in and the rear fan blowing out gave me the best temps.

    Just try to experiment a little and see which seems to work the best.

    Regards Howard :grinthumb
  4. NeonShadow

    NeonShadow TS Rookie Topic Starter

    Alright. I see and understand how the air flow should be going. I got 4 fans. 1 at the top of the case, 1 at the side, and 2 in the back.

    One other question. How would if a fan is blowing air in or out? Tie a string to them?

    Thanx for your guys help. :)
  5. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Please do not tie anything to your fan grills.

    If you use a thin piece of paper you will be able to tell which fans are sucking air into your case and which fans are blowing air out of your case.

    Regards Howard :grinthumb
  6. acidosmosis

    acidosmosis TechSpot Chancellor Posts: 1,350

    You could always light a cigarette, suck a lot of smoke into your mouth and blow it into the case and you will be able to see exactly how the air is flowing :p. Tar = Bad for hardware.
  7. Electrick Gypsy

    Electrick Gypsy TS Rookie Posts: 76

    Bugga - - tried that.
    My computer coughed once and ejected both drive trays and hit me in the forehead. :)~
  8. blaacksheep

    blaacksheep TS Rookie Posts: 70

    You got it easy. My computer is up to a 2 pack a day habit, now!! :D
  9. Tarkus

    Tarkus TechSpot Ambassador Posts: 621

    the fan blows air towards it's hub support bars. Some fans (not many these days) even have an arrow on the side as a guide.
  10. fishhookz

    fishhookz TS Rookie Posts: 79

    Typically, intake in the lower front sucks cool air in, exhaust in the higher back and blowhole in the top blow warm air out.

    Remember this: heat rises.

    So most tower cases are designed to accommodate fans like the way I mentioned.

    As for the side fan, it depends on the CPU fan. I reversed my CPU fan to suck air from the heatsink, and my side fan to blow that air out. Some had ever stacked two Intel CPU fans together in the opposite directions to increase the air flow. It works like a Panaflow.

    Lastly, you'd want to have more intakes than exhausts to "pressurize" the interior with cool air. A 120mm fan would do the trick.
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