Why do manufacturers ship HSF with the fan blowing on the heatsink?

VIAN

Diamond Member
Aug 22, 2003
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Why is it that manufacturers always sell their HSF with the fan blowing on the heatsink, is there something I missed here. I always turn my fans upside down and have the air sucked out of the case instead of the fan blowing onto the heatsink and causing turbulence with the case fan next to it and creating more heat. Is there a better way?
 

beatle

Diamond Member
Apr 2, 2001
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Originally posted by: VIAN
Why is it that manufacturers always sell their HSF with the fan blowing on the heatsink, is there something I missed here. I always turn my fans upside down and have the air sucked out of the case instead of the fan blowing onto the heatsink and causing turbulence with the case fan next to it and creating more heat. Is there a better way?

The only manufacturer I know of that reccommends having the air sucked away from the heatsink is Alpha. Even then, you can sometimes achieve better results by turning the fan around and removing the shroud. Try it!
 

Sid59

Lifer
Sep 2, 2002
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try both.

stupid dust bunnies lived in the slk800 when i had the fan blowing on the heatsink,
 

VIAN

Diamond Member
Aug 22, 2003
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Well, I think that sucking the heatsink and out the case is best. It works better for me. I remember when I first changed to this method, I lowered my temp by 10C, it was amazing. you should try it.

From my experience: Blowing is better, but thats when you dont have the rest of the case to worry about. In an open case, blowing is the best solution; sucking will just be as good and may not cool as effectively. Inside a closed environment though, it makes sense to get rid of the heat. having a fan sucking hot air from the heatsink and then having a fan next to it suck it out is the best move.
 

EeyoreX

Platinum Member
Oct 27, 2002
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Why is it that manufacturers always sell their HSF with the fan blowing on the heatsink
Because it works? Unless you have a duct directly out of your case from the heat sink fan, you aren't exhausting the hot air from the case,, you are still just "creating turbulance", and on top of that not getting any air to the hot CPU core. How much air do you think is moving when you have the fan against a semi-solid object (the heatsink) compared to the airflow from the ambient air in the case (much lass solid than a heat sink)? You want cool air blowing on the heatsink, except in cases like the Alpha, and even then sometimes you still want that. If you have better results, more power to you. Most people will find having the fans blow air on the heatsink to yeild cooler CPUs.

\Dan
 

pspada

Platinum Member
Dec 23, 2002
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blowing has beat sucking every single time, in my experience. And I'm not sure what you're thinking, but yer a sick, disturbed person. :disgust:
 

ToxicWaste

Member
Dec 6, 2003
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How many times does this question get asked and answered? When it comes to CPU fans, it's better to blow than to suck.

YMMV,
Toxic
 

Gravity

Diamond Member
Mar 21, 2003
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Well, it seems that there is more airflow to the affected area when blowing. When sucking you get air that travels the shortest distance to go throught the fan. The air has to endure the turbulance of getting into the fins when sucking whereas in blowing, the air is forced into the fins and into the area where the heat is greates, near the cpu core.

Blowing is best but if you suck and get good results you might want to just keep it to your self.
 

SWScorch

Diamond Member
May 13, 2001
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In MOST cases heatsinks work better when the fan is blowing air into them. Why is this, you ask? Think about it: when the fan is blowing into them there all that pressure behind it, and the air is forced through the fins all the way down to the base and out. When the fan is sucking air away from the ehatsink, the pressure is facing away from the heatsink, and so the air is moving very slowly and weakly around the heatsink fins. Furthermore, the surface area that the air is being drawn from is larger, and most of the air will be drawn from the top of the heatsink, leaving the base (the hottest part) starved.

In certain cases, however, it will work more efficiently to draw the air away; for instance if you have a shroud to draw air in around the base of the heatsink, and/or if you immediately exhaust the air being drawn from the heatsink.
 

huesmann

Diamond Member
Dec 7, 1999
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The only time you will have better results sucking the air out of the heatsink is if the air where the fan is blowing to is warmer than the air around the heatsink, i.e. rarely, if ever. In most (really all) situations the fan will be sucking cooler air and blowing into the hotter heatsink.
 

xCygnusX1x

Senior member
Mar 4, 2002
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i always like this analogy...

when you are hot in the summer time, and go to turn a fan on, do you make the fan blow air on you, or stand behind it and try to have it suck the heat off your body?


 

Overkast

Senior member
Aug 1, 2003
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Originally posted by: xCygnusX1x
i always like this analogy...

when you are hot in the summer time, and go to turn a fan on, do you make the fan blow air on you, or stand behind it and try to have it suck the heat off your body?

Perfect analogy.