#1
  1. !Ruff Ryder!
    Devshed Novice (500 - 999 posts)

    Join Date
    Jun 2004
    Location
    Québec, Canada... Represent!
    Posts
    689
    Rep Power
    13

    Reversing direction of CPU fan.


    I think it's kind of wierd that the processor fans blow air right into the heatsink since this makes the whole case very hot. Would it be any better if, for example, the fan was reversed (blowing air away from the HS) and the hot air was blown directly outside the case or is this less effective?

    EDIT: hahaha airsink
    My b0x:
    AMD XP Barton 2800+ @ Stock speed... (going up again soon in winter!!!)
    2 x 512MB Kingston RAM for 1GB dual channel
    1 x 120GB HDD (soon another ) ( <-- God I've been saying this for like a year )
    SoundBlaster Audigy 2 ZS (0wN5!!!)
    Logitech Z-5300 speakers (0wN5!!!)
    ATI All-In-Wonder 9800 Pro (0wN5!!!)
    Black ViewSonic A91f+@1280x1024@75Hz (0wN5!!!) (Well, too bad I can't go 1600x1200 above 60Hz )

    If I helped you out please consider helping a poor college student get a free iPod for his long commute by signing up here with my referal link:
    My Link
    (I will pay you $10-$20 if you want to cover the cost of the offer for you. ***This ISNT a scam. I personally know a girl who recieved one a few months ago!***)
  2. #2
  3. Just another guy
    Devshed Frequenter (2500 - 2999 posts)

    Join Date
    Jun 2003
    Location
    Wisconsin
    Posts
    2,953
    Rep Power
    262
    Picture a room fan. If you put your hand in front of it, the air blows on it. If you put your hand behind it, you might feel a little movement of air, but not much.
    Same with a heatsink. You want as much air to move past the vanes of the heatsink as possible, so that the air can carry away heat. If you reversed the direction of the fan, air would move past the heatsink very slowly, which wouldn't be effective. If you have a fan in the side of your case, you can make that fan blow in onto the heatsink, so that cooler outside air is going past the heatsink. Reversing the direction of the CPU fan would be counter productive (no pun intended )

    Comments on this post

    • gt3_dk agrees : Great
    • medialint agrees
    --Dave--

    U2kgSG9jIExlZ2VyZSBTY2lzLCBOaW1pdW0gRXJ1ZGl0aW9uaXMgSGFiZXM=

    My hobby: collecting US coins
  4. #3
  5. !Ruff Ryder!
    Devshed Novice (500 - 999 posts)

    Join Date
    Jun 2004
    Location
    Québec, Canada... Represent!
    Posts
    689
    Rep Power
    13
    Thanks for the reply it was very clear.
    My b0x:
    AMD XP Barton 2800+ @ Stock speed... (going up again soon in winter!!!)
    2 x 512MB Kingston RAM for 1GB dual channel
    1 x 120GB HDD (soon another ) ( <-- God I've been saying this for like a year )
    SoundBlaster Audigy 2 ZS (0wN5!!!)
    Logitech Z-5300 speakers (0wN5!!!)
    ATI All-In-Wonder 9800 Pro (0wN5!!!)
    Black ViewSonic A91f+@1280x1024@75Hz (0wN5!!!) (Well, too bad I can't go 1600x1200 above 60Hz )

    If I helped you out please consider helping a poor college student get a free iPod for his long commute by signing up here with my referal link:
    My Link
    (I will pay you $10-$20 if you want to cover the cost of the offer for you. ***This ISNT a scam. I personally know a girl who recieved one a few months ago!***)
  6. #4
  7. No Profile Picture
    Registered User
    Devshed Newbie (0 - 499 posts)

    Join Date
    Jun 2006
    Posts
    2
    Rep Power
    0

    Exclamation Fan Blows Air Out


    Originally Posted by gt3_dk
    Thanks for the reply it was very clear.
    If you have an attic fan you know it blows the hot air OUT of the attic. Would it not make sense that it walso be the most effective direction to cool your case?
  8. #5
  9. Providing fuel for space ships
    Devshed Supreme Being (6500+ posts)

    Join Date
    Mar 2004
    Location
    nr Edinburgh, Scotland
    Posts
    14,382
    Rep Power
    3848
    I think we've established that.
    The No Ma'am commandments:

    1.) It is O.K. to call hooters 'knockers' and sometimes snack trays
    2.) It is wrong to be French
    3.) It is O.K. to put all bad people in a giant meat grinder
    4.) Lawyers, see rule 3
    5.) It is O.K. to drive a gas guzzler if it helps you get babes
    6.) Everyone should car pool but me
    7.) Bring back the word 'stewardesses'
    8.) Synchronized swimming is not a sport
    9.) Mud wrestling is a sport
  10. #6
  11. Thinking!
    Devshed Newbie (0 - 499 posts)

    Join Date
    Nov 2004
    Location
    Scotland
    Posts
    140
    Rep Power
    206
    Originally Posted by DoctorPissoff
    If you have an attic fan you know it blows the hot air OUT of the attic. Would it not make sense that it walso be the most effective direction to cool your case?
    That's why cases have exhaust fans to remove hot air. But you also need intake fans to provide a constant movement of cold air throughout.

    Reversing the fan on the Heatsink wont help cool the cpu, it might take some heat away, but not nearly as much as cold air flowing over the aluminium fins on a heatsink.

    Manufacturers take so much time in perfecting a copper based aluminium fin heatsink for a reason.
  12. #7
  13. No Profile Picture
    Registered User
    Devshed Newbie (0 - 499 posts)

    Join Date
    Jan 2004
    Posts
    20
    Rep Power
    0
    I've seen a couple mods where the user reversed the flow and it worked just fine. Both used the flower heatsink design from Zalman. A duct was fitted over the top of the heatsink after the fan was removed, and the duct was attached to the rear case fan. This pulled air through the fins of the heatsink and then directly out.

    The cooler the incoming air the better however; your cpu will be cooled better by ducting air to the cpu using the normal push path rather than sucking it out.

    www.silentpcreview.com is a good site to check out PC cooling with a focus on low noise, it's where I found that cpu duct design.
  14. #8
  15. No Profile Picture
    Registered User
    Devshed Newbie (0 - 499 posts)

    Join Date
    Jun 2006
    Posts
    2
    Rep Power
    0
    Originally Posted by IceDragon
    That's why cases have exhaust fans to remove hot air. But you also need intake fans to provide a constant movement of cold air throughout.

    Reversing the fan on the Heatsink wont help cool the cpu, it might take some heat away, but not nearly as much as cold air flowing over the aluminium fins on a heatsink.

    Manufacturers take so much time in perfecting a copper based aluminium fin heatsink for a reason.
    If you have an exhuast fan, with a passive intake opening elsewhere you don't need and intake fan. The exhaust fan will draw in the same amount of air it dispalaces.
  16. #9
  17. No Profile Picture
    Registered User
    Devshed Newbie (0 - 499 posts)

    Join Date
    Aug 2006
    Posts
    1
    Rep Power
    0
    I am having a problem where my CPU fan is blowing air out of the case. Much like what you wanted to try, lol (that's the way it came). And as you've stated and many have told me, it should be blowing air in.
    Is there any way the reverse the fan?
    The way it's made, I can't just simply put it on backwards.

    Thank You.

IMN logo majestic logo threadwatch logo seochat tools logo