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  1. #1
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    Should a Side Fan Blow in or Blow Out?

    I did some research on this topic and most agree it should blow into the case (a search on this site and forum)! This seems wrong to me. What is your opinion? My machine has a front fan that sucks air in and a rear fan that blows air out. I would think that a side fan should pull the hot air off the cpu heat sink and blow it out.

    DFI NF570-M2/G
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    Lou_The_Blue_Guru - For those working with computers that haven’t figured this out yet: "Everything is related with every other thing ... " -- The Jaina Philosophy of Non-Absolutism

  2. #2
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    Re: Should a Side Fan Blow in or Blow Out?

    You have a front fan blowing in, and a rear fan, and the PSU sucking air out.

    1 extra fan blowing air in, evens the flow volume out.
    ......
    ................. Heat .....................

    24/7 speeds
    w/c - * GA-EP45-UD3P - Q9650 - 3737 - 9x415 * ...cpu-z... w/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 170 - 2925 - 9x325 * ... cpu-z ... w/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 170 - 2826 - 9x314 * ... cpu-z ... a/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 165 - 2250 - 9x250 * ... cpu-z ... a/c - GTS250

  3. #3
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    Re: Should a Side Fan Blow in or Blow Out?

    in from front,side,bottom. out from top,rear

    add a couple 120mm fans overhead to drop temps by 10+ celsiusD.S.C-12(2)-disclaimer : whatever u do with your hardware/software is your
    responsibility, which i dont hold if u break anything

    GRAB here OcBible v1.55 and Guidemania v1.21
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  4. #4
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    Re: Should a Side Fan Blow in or Blow Out?

    The area around the CPU fan is generally surrounded by hot air. The side fan draws cool air from outside of the case directly to the CPU fan, which is why many of them have the funnel. The outside air should be cooler than the air inside the case.

  5. #5
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    Re: Should a Side Fan Blow in or Blow Out?

    In addition, 99% of all CPU fans blow down onto the CPU, so if a side fan is directly opposite the CPU fan, and blowing in opposite direction, they will fight each other and reduce the effectiveness of both. But as always, try it both ways and see what your case temps are. Sometimes things just work against logic!

  6. #6
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    Re: Should a Side Fan Blow in or Blow Out?

    i also tend to leave the backplate out of the equation soemtimes. bit more breathing for that cramped area

    add a couple 120mm fans overhead to drop temps by 10+ celsiusD.S.C-12(2)-disclaimer : whatever u do with your hardware/software is your
    responsibility, which i dont hold if u break anything

    GRAB here OcBible v1.55 and Guidemania v1.21
    scary pooch?pooch#1taking ball from dogpooch pulln on ropeme on board after 2 years
    of no board
    http://gonny.se/ <-cool lady http://www.mediafire.com/?8dmg21ms1vx
    IN MEMORY OF HOW BM WAS TREATED HERE...

  7. #7
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    Re: Should a Side Fan Blow in or Blow Out?

    Well, I appreciate all of the feedback. Note the Coolermaster heat sink fan blows air form the front, through the HS, to the back of the case in my system, not from the top down. Based on the heat funnel idea with the funnel channeling air from the HS to the outside of the case, it seemed to me the side fan should blow air from over the HS to the outside of the case. My case did have a funnel but the HS was so tall I had to remove it.

    OTOH, I can appreciate the point of view that says the side fan should blow cooler air from outside the case onto the HS. Given fan speeds, this would build up pressure inside the case and cause greater airflow out the back of the case.

    In conclusion, I don't think anyone has a definitive answer, so as was suggested I need to try both approaches. If anyone is interested, I can report back.

    Note: I'm not sure how the PS fan factors into this equation.
    Last edited by LouTheBlueGuru; 07-22-2007 at 10:20 PM.
    Lou_The_Blue_Guru - For those working with computers that haven’t figured this out yet: "Everything is related with every other thing ... " -- The Jaina Philosophy of Non-Absolutism

  8. #8
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    Re: Should a Side Fan Blow in or Blow Out?

    Actually you would want positive pressure inside the case, that way if the PSU fan increases speed it will not be starving for cool air.

    Also helps keep the dust bunnies out.

    And yes report back with you findings, it will help some else down the road with the same question.
    ......
    ................. Heat .....................

    24/7 speeds
    w/c - * GA-EP45-UD3P - Q9650 - 3737 - 9x415 * ...cpu-z... w/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 170 - 2925 - 9x325 * ... cpu-z ... w/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 170 - 2826 - 9x314 * ... cpu-z ... a/c - GTX260
    w/c - * A8N32-SLI-Dlx - Opty 165 - 2250 - 9x250 * ... cpu-z ... a/c - GTS250

  9. #9
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    Re: Should a Side Fan Blow in or Blow Out?

    I have an 80mm fan on the side of my case and have tried it both ways. I noticed really no obvious temperature changes with it blowing in vs. out, BUT when it was blowing out, i noticed my HS fan making more noise, i figure from the struggle between the fans. So I turned it in as an intake fan and added a second 80mm fan blowing out the back. Just thought I would add my .02 from experience. Of course all cases and fans are different and my side fan is directly across from my HS and my HS fan blows down onto the HS, not across it like yours does. So definitely try it both ways and report back, i'm interested to see what results you get.

    Rob

  10. #10
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    Re: Should a Side Fan Blow in or Blow Out?

    Air pressure for me is a moot point. You're always gonna get dust bunnies in a dusty or carpetted area and air will still find a way out. Fans simple accelerate the process. In any case, more airflow out of the back of the case is a good thing because the fans/vents there are high up and close to the main hot spot (near the CPU, VGA card and chipset).

  11. #11
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    Re: Should a Side Fan Blow in or Blow Out?

    good air flow design is the more elegant method, bring it in low from the front and exhuast it high out the back, but keeping it moving back to front with as little resistance as possible is what i find works best.

    the brute force approach of putting tons of fans blowing in and out from all points is indeed effective, but not very efficient i should think. it creates turbulance which may negate the effects of other fans in the system.

    until someone does some indepth highly scientific study it's like the world will never truely know.

    i also like positive pressure.
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  12. #12
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    Re: Should a Side Fan Blow in or Blow Out?

    Quote Originally Posted by LouTheBlueGuru View Post
    I did some research on this topic and most agree it should blow into the case (a search on this site and forum)! This seems wrong to me. What is your opinion? My machine has a front fan that sucks air in and a rear fan that blows air out. I would think that a side fan should pull the hot air off the cpu heat sink and blow it out.

    DFI NF570-M2/G
    AMD 64 X2 5600+ @ (14x200) with Cooler Master Hyper TX
    4x1024 Corsair XMS PC2 6400 @ 4-4-4-12(2.1v), 2T
    Corsair 520 PS
    XFX 8600 GT Video
    WD3200AAKS 320 Gig
    Emu 0404
    Abit AirPace wireless Nic
    OS - none execept DOS 6.2 on occasion
    My temps are a little on the Hot side. I'm running about 55 c CPU and 35 c system temp.
    If I remove the side cover I can see the temp drop to 25 c System and 45 c CPU.
    I'm going to add a fan to the side cover right over the CPU fan. Hopefully this will keep the temps low with the side cover in place.
    I'm not sure if the fan size will be 80mm or 92mm. I'll let ya know.
    Pete

  13. #13
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    Re: Should a Side Fan Blow in or Blow Out?

    Here is how Silverstone laid out the cooling for the TJ07:

    Cooling System
    Top: 2 x 120mm exhaust fan, 1200rpm, 21dBA
    Rear: 2 x 92mm intake fans, 2100rpm, 23dBA
    Bottom: 2 x 120mm intake fan, 1200rpm, 21dBA

    Because I did not use the HDD case in the bottom of the case, I disconnected the lower fans and installed a 120mm side fan to assist the CPU cooling.
    Asus M8Z77-V Deluxe
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  14. #14
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    Re: Should a Side Fan Blow in or Blow Out?

    Quote Originally Posted by richardd43 View Post
    Because I did not use the HDD case in the bottom of the case, I disconnected the lower fans and installed a 120mm side fan to assist the CPU cooling.
    why? the front fans would likely aid cooling better ythan the one on the side. better more efficient airflow.
    Corsair 800D / Corsair TX750 PSU
    ASUS Sabertooth P67 / Win7 Pro
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    The member formerly known as SuBX3r0 HEAT

  15. #15
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    Re: Should a Side Fan Blow in or Blow Out?

    The TJ07 does not have a front fan. The lower fans are part of the 2 HDD cages and suck air in one side and blow it out on the other. As these cages are mounted on the very bottom of the chassis I saw no need for them to be on. They would contribute little to the overall case temperature.

    In fact, I removed one of the cages to better accommodate the wiring from the 2 PSUs that are installed (also in the bottom of the case).
    Asus M8Z77-V Deluxe
    Intel 3770K
    G-Skill 1600 16G
    Corsair H100
    EVGA 670 GTX
    2 Corsair Force 3 120G (Raid 0)
    2 x Seagate 1T 6G
    2 Samsung SyncMaster T260HD Monitors
    Thermaltake Level 10 UGK
    Silverstone Olympia OP1000 1000W
    Windows 8

    Never argue with idiots, they will drag you down to their level and beat you with experience.

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