Should the CPU fan blow, or pull air on the heatsink?

Discussion in 'PC hardware help' started by i_am_alex, Nov 22, 2008.

  1. i_am_alex

    i_am_alex Regular member

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    I bought a Thermalright True Copper (don't cry :p) and I bought a Delta fan which moves 220CFM. I have to stick this fan to the side of the heatsink. Did I want the fan to blow air through the heatsink, or pull it off?
    [​IMG]
    Soz bout dodgy paint style.

    Title is meant to say pull off btw :p
     
    Last edited: Nov 22, 2008
  2. ugc

    ugc Regular member

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    I would say it doesn't matter. Just put it in relationship to the other fans you have in your case (you don't want them fighting for air, so to speak).
     
  3. cee43ja1

    cee43ja1 Active member

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    you want it to blow air into the heatsink. and the direction of the air should be going to the exhaust fan.
     
  4. ddp

    ddp Moderator Staff Member

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    onto the heatsink not away from it.
     
  5. ugc

    ugc Regular member

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    ok guys, educate me on this one.

    If it sucks, or blows, it draws the same amount of air across the fins of the heat sink.

    Take other things for example too...like the radiator in your car, and the transmission cooler, all are setup to suck air, not blow.

    **EDIT for Science**
    The following are copy and paste arguments on the subject

    Guy 1 "Now think about it from a scientific point of view. Cold air is denser then hot, so if the fan were rotating with the same speed in both cases, you would move more atoms with each rotation if you push the air, but you would need more energy because the mass is greater. If you push the air the energy converted into heat by running the fan would blow over the CPU. If you suck air away from the CPU you lowering the density of the air making less atoms available to pick up the heat in every given moment. Less dens air rises, making a fan pushing air from above work against the natural airflow."

    Guy 2 "One comment I'd like to add to this thread that hasn't been discussed: The exhaust from a fan is turbulent, while the intake is not. Turbulent air tends to cool better. So by that argument, blowing should work better. On the other hand, I've seen some heat sink arrangements that suck air through the heat sink, and then blow it directly out of the case. Since you are not recycling the hot air inside the case, this method can also be very efficient. I guess it just boils down to the overall design."
     
    Last edited: Nov 23, 2008
  6. i_am_alex

    i_am_alex Regular member

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    Tyvm. I set it up and it's very loud as expected, but this stupid mobo doesn't let me tune down power fans. So i gotta get a fan controller 2moz.
     
  7. ddp

    ddp Moderator Staff Member

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    ugc, it depends on were the fan is attached to as on the tower side(s) or on the heatsink. on the side(s) then the fan(s) can be blowing air out of the tower or sucking air in to the tower. on the heatsink you want the fan to blow air into the heatsink to keep it cool. if you are hot, do you have the fan blow air at you or away from you?
     
  8. onya

    onya Guest

    Oh dear...oh my...

    ...although you do have a certain point, some cars do suck. lol.
     

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