Best layout for 4 case fans

Discussion in 'Cases & Cooling' started by Vicaar, Nov 24, 2012.

  1. Vicaar

    Vicaar Member

    Joined:
    May 29, 2009
    Messages:
    74
    Likes Received:
    0
    In a mid-size ATX case, given 4 120mm fans what would be the 'best' use? This would be a NZXT 210 Source Elite case.

    The case comes default with a rear and top fan (bottom-mounted PSU). I have two extra 120mm fans:
    * Mount both in front
    * Mount one in front, and one bottom

    I realize the answer might be 'test it both ways and check temps', but figured someone may have already done this :)
     
  2. Charlie98

    Charlie98 Diamond Member

    Joined:
    Nov 6, 2011
    Messages:
    5,818
    Likes Received:
    0
    Given what I've been reading about positive case pressure... I'd mount both in front and cover the bottom port. It's what I have done (sort of) with my case trying to eliminate dust and keep the CPU and GPU cool...
     
  3. lehtv

    lehtv Lifer

    Joined:
    Dec 8, 2010
    Messages:
    11,574
    Likes Received:
    3
    Two in (front)
    Two out (rear and top)
     
  4. MrK6

    MrK6 Diamond Member

    Joined:
    Aug 9, 2004
    Messages:
    4,438
    Likes Received:
    0
    It really depends on your specific case and intentions. I've found the best results (in respect to cooling vs. noise) come from having directed airflow, so either front to back or bottom to top, but not both. If you wanted to stick to positive case pressure first, try mounting two fans in the front, one in the back + the PSU. Another thing to consider is noise, some cases are louder with negative pressure, some are louder with positive pressure. Unless you test it's difficult to say.
     
  5. kleinkinstein

    kleinkinstein Senior member

    Joined:
    Aug 16, 2012
    Messages:
    823
    Likes Received:
    0
    I'm no fluid mechanics guru, but from what I gathered from other sources (notably Silverstone) and some knowledge gained back as an engineer in school, I thought of the following:


    • You'll want more air per given space in the case than in the environment. So-called positive pressure. This has the effect of all the little cracks in your case pushing air out (mitigating dust build up) and prevents recycling of hot exhaust air (which some will get sucked into the holes that don't have a fan blowing out). So this implies that your intake CFM should be greater than your exhaust CFM.
    • While having a clean stream of air from one end of the case to the other is ideal, I don't think it really matters. Here's the thing: if a component needs airflow to cool down, it will have a fan with it. This fan will blow air across it better than any airflow the case fans could generate. Not to mention, I'm pretty sure a fan cannot accelerate air faster than a given velocity. A fan is designed to push air, on the same token, air can push a fan.
    • Top exhaust fans are counter-intuitive if your intake CFM < output CFM. Yes, convection does cause hot air to rise and perhaps collect, but most of the heat is in the middle, where your graphics cards are. The average temperature inside the case is going to rise before top exhaust fans will have any real effect.
    • On that note, the idea for the intakes it to bring in cold air as much as possible, thereby lowering the average temperature inside the case. This is so active cooling components have cooler air. Yes you could lower the average temperature in the case by blowing out hot air, but you run the risk your case having negative air pressure. Not only that, a top fan that's an intake would blow colder air directly on your VRMs and Processor... so doesn't that sound more beneficial?

    In any case, this video convinced me of a lot of how to set up fans and design pressure in all my builds.

    http://www.youtube.com/watch?feature=player_detailpage&v=Qe-2ZqmSGug
     
  6. FreeAtLast2012

    Joined:
    Dec 29, 2011
    Messages:
    33
    Likes Received:
    0
  7. Charlie98

    Charlie98 Diamond Member

    Joined:
    Nov 6, 2011
    Messages:
    5,818
    Likes Received:
    0
    I actually have a 4-fan controller... I run the intake fans at a higher RPM than the exhaust fans to try to achieve positive pressure (in my swiss-cheese of a case.)
     
  8. Rhezuss

    Rhezuss Diamond Member

    Joined:
    Jan 31, 2006
    Messages:
    4,037
    Likes Received:
    2
    So:
    - Intake 1-140mm front + 1-120mm bottom
    - Exhaust 1-120mm rear + 1-140mm top

    Is not that good?

    I have de CM 690 II Adv which came with 1 front 140mm and 1 top 140mm. I added 1 rear 120mm for exhaust and it's going well. When I add 1 side intake it's making an annoying noise due to the mesh so I removed it and placed it in the bottom.

    Should I rethink the airflow?
     
  9. bunnyfubbles

    bunnyfubbles Lifer

    Joined:
    Sep 3, 2001
    Messages:
    12,250
    Likes Received:
    0
    This is another reason why I love the FT02, no other way to do it with this case

    Recently finished a water cooling job on a Fractal Arc Midi that was something of a nightmare with how often I had to keep going back and making mods because I tried to do everything with 140mm fans, but needed part of the 5.25 bay trimmed away to fit my XSPC EX280 dual 140mm rad. Anyway, when that was all done I then wanted to set up intake fans and try to minimize noise using only 140mm

    I'm currently with 2 x 140mm intakes on the front, 1 x 140mm intake on the bottom, and 2 x 140mm exhaust on the top where the rad is

    I have yet to decide what or if I'm going to do anything with the rear or side ports. I'm thinking I might just make the rear another intake and just exhaust everything out the top, but I would want to get a filter on it as the front and bottom intakes have filters

    The side would be an intake if I used it, and can take a 140mm fan or even a 180mm fan, but again, I would want to put a filter on it somehow
     
  10. tracerbullet

    tracerbullet Golden Member

    Joined:
    Feb 22, 2001
    Messages:
    1,543
    Likes Received:
    4
    Not to make things worse, but some other things to consider (may have been mentioned, if so, sorry I didn't see):

    PSU will be a factor, normally pulling air out of a case, and at varying speeds depending on usage
    Video card as well, depending on design
    Intake fans will collect dust, I've found it's good to keep them where they can be easily vacuumed once in a while

    W/ that case I kind of like the bottom fan blowing inwards, sending cool air near the PSU to steal from, and the rest towards the video card. 2 front fans blowing inwards as well, all of it moving air not just towards the video card but bringing cool air inside and towards the CPU as well. The rear fan blowing out, guessing that with everything assembled if you have a good sized air cooler you'll be really close to it and blowing air that direction already. Top fan... in or out depending on proximity to the CPU cooler? Probably out.

    Just an opinion...