Are intake fans worthless?

Discussion in 'Computer Information' started by Matthew Superstar Swass, Oct 2, 2004.

  1. Unless you've got more (or far more powerful) intake fans than exhaust fans,
    then it seems like the intake fans are a waste.

    If air is being blown out, then it's being sucked in with or without the intake
    fans. Example...

    40 cubic feet per minute exhaust
    50 cubic feet per minute intake

    This would be the equivalent of only 10 cubic feet per minute intake since the
    exhaust is going to bring in 40 no matter how you look at it.

    I'm considering moving my intake from the bottom front to the back and making
    it an exhaust. Right now it seems like the PSU fan would be canceling out most
    of the intake.
    Matthew Superstar Swass, Oct 2, 2004
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  2. Matthew Superstar Swass

    Drifter Guest

    I don't consider intake fans a waste -if some planning is used-. For
    example, I have sealed up my case pretty tightly and have dust screens
    over the intakes. I have arranged ducts in my machine so that one
    intake fan blows over the two hard drives and the other intake fan
    empties next to the CPU and the video card heatsink. This ensures
    that the coolest air is dumping directly where it is needed most and
    also the use of intake fans overcomes the resistance created by the
    filters. As a result my case stays pretty darn clean inside and I
    still have very good airflow.

    "I've been here, I've been there..."
    Drifter, Oct 2, 2004
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  3. Matthew Superstar Swass

    Thor Guest

    They aren't worthless. For one thing you are controlling to a significant
    degree, where the fresh air is coming from. If you just set up multiple
    exhaust fans, then the fresh air draw will be from wherever the air can
    enter the case, and often through your optical and floppy drives etc., which
    often results in a lot of dust buildup in these devices. Having a front
    mounted fresh air intake fan, ensures that you are bringing in fresh air
    where you want it brought in, and not through less optimal or desirable
    sources. You can also improve the airFLOW by setting up a constant air
    current, rather than a less vigorous circulation that is based on bringing
    in air from a number of different locations simultaneously with no
    particular directional flow pattern.
    Thor, Oct 2, 2004
  4. Matthew Superstar Swass

    ric Guest

    The above shows you need to brush up on your CFM theory. If a fan is rated
    at 40 CFM, it is 40 CFM *only* at zero static pressure. Inside of a case,
    is subjected to a lot of static pressure, and won't deliver even close to
    the 40 CFM.

    Adding an intake fan accomplishes two things: 1) it reduces the static
    pressure seen by the exhaust fan (greatly increasing its CFM), and 2) it
    directs more of the incoming air to the intake opening, where a dust
    filter can partly clean the air before it enters.

    So, adding an intake fan *does* improve things even if its CFM rating is
    less than that of the exhaust fan.
    ric, Oct 2, 2004
  5. Matthew Superstar Swass

    Plato Guest

    Many pcs have only one spot to put a second fan in and that's often in
    front-bottom. If so then you make that an intake. If the only spot you
    have is in back under the power
    supply then you make that an exhaust.

    Most PCs are fine right out of the box with only the power supply fan
    doing all the
    work. Note however, that a good majority of pc cases do have a spot for
    an additional fan for a good reason. When you start adding additional
    hard drives or super duper
    video cards the additional cooling is recommended.

    A second case fan may however, be good insurance even if you have a
    simple system. Reason being is that the power supply acts like a vacuum
    cleaner and accumulates hoards of dust inside resulting in poor airflow.
    The second fan will help during the time
    between blowing out your PS when you open the case for maintenance or
    adding hardware.
    Plato, Oct 2, 2004
  6. Matthew Superstar Swass

    Harold Wiles Guest

    Plato, <|@|.|>, the myotic, amateur horse's feedbag, and wig maker to
    well-heeled Chihuahuas, caviled:

    Why would you put an intake fan on a vagina? Are you a sexual deviant or
    Harold Wiles, Oct 2, 2004
  7. If you just set up multiple
    Having an intake fan does not stop this unless the intake is so powerful that
    it's creating pressure within the case, and blowing air out through openings
    around the said drives.
    Matthew Superstar Swass, Oct 2, 2004
  8. Matthew Superstar Swass

    Thor Guest

    Even if it isn't enough to create a pressurized case, having an intake fan
    will still greatly reduce the amount of intake draw from those other
    openings. It need not be so powerful that it is forcing air *out* of those
    places. It only needs to ameliorate the vacuum strength at those places by
    bringing enough fresh air at a chosen location to cancel out some, or all
    the vacuum inside the case. They are still a big benefit for the reason I
    described. Creating a pressurized case isn't a good idea either because some
    of the dust that is sucked in can get blown *out* of those places, leaving
    some behind inside the optical and floppy drives. The best solution is to
    equallize or at least minimize the difference in pressure inside and outside
    the case, while creating a good airflow across internal components. An
    additional intake fan can accomplish that, when you have an over abundance
    of exhaust capacity.
    Thor, Oct 2, 2004
  9. Matthew Superstar Swass

    Spajky Guest

    something similar I´ve done also & I completely agree with this
    statement. I made myself such a good air flow thru the case, that my
    calibrated temp sensors show practically no difference if I have the
    cover on the case or not. And its a Desktop which is harder to do it
    than Tower setup.

    ..... well, it took me few few weeks campains thru last 4 y to do it,
    but it was worth (silence wise) ... pics you can see on my site ...
    Spajky, Oct 2, 2004
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