On or Off

G

geRm

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May 11, 2005
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Im just a tab confused on something dealing with cooling. I keep seeing that fans on CPU and GPUs pull/push air on to it.

Which is it. Fans pull air off, or put air on?
 
Megadeth_Guy01 said:
On, always, if you're talking about heatsinks.
Click to expand...
So if there is fan on the heat sink air will be pulled off, and if no heat sink pulled on?
 
KaptainBlaZzed said:
the air is almost always pushed onto the heassink, twords the mobo
Click to expand...
Very few people do this, it substantially increases temperatures over what most people run.
This is how your fan should work:
untitled4uw.gif


All of those Zalmans, the TT Big Typhoon, etc all pull air away from the mobo/heatsink.
 
Oline61 said:
Very few people do this, it substantially increases temperatures over what most people run.
This is how your fan should work:
untitled4uw.gif


All of those Zalmans, the TT Big Typhoon, etc all pull air away from the mobo/heatsink.
Click to expand...
My zalman cnps7700-cu pushes air toward the motherboard, I just took off my case door and checked.
 
untitled6xq.png

Looking at the fan blades on any of these units, it is quite obvious which way air flows. It's not very complicated.

EDIT: To make it simpler, think of this. The air picks up heat going through the heat sink. If this heated air blew down, towards the motherboard it would increase temperatures, however if it blew out and away from the motherboard, it wouldn't. :D
 
you are wrong, how many BT's do you have???

look at the fan, Fans always blow the air twords the cross supports that support them.
Do you see any cross supports in that picture.....NO
because they are on the other side of the fan, thus blowing the air onto the HSF.

you could also look at the curvature of the blades on the fan. they are curved in an upward shape, thus making it an optimal configuratin to blow the air down.

why don't you go look at some fans and then come back and tell us what you have learned.
 
Oline61 said:
untitled5kb1.png
Click to expand...


If you draw the arrows in the wrong direction, sure. The fan does not spin in the direction that you are drawing, it spins opposite, blowing air ONTO the motherboard. I have the Zalman 7700 Cu and the 9500 Cu LED and just check fan direction. It blows downward.
 
KaptainBlaZzed said:
you are wrong, how many BT's do you have???

look at the fan, Fans always blow the air twords the cross supports that support them.
Do you see any cross supports in that picture.....NO
because they are on the other side of the fan, thus blowing the air onto the HSF.
Click to expand...
I own no BT's, but if you are telling the truth, your BTs are wired incorrectly, and decreasing your cooling performance. I have also never seen a fan with these mysterious "cross supports" either. After looking at many popular fans such as the high performance Deltas, Panaflos, Vantec Stealth, Vantec Tornado, etc I see nothing resembling what you describe as a cross support. In addition having helped a friend install a BT over his 3000+ Winnie I know for a fact there there are none of these "cross supports" on a BT, and that the air rises away from the motherboard. A far more reliable way to look at airflow is this diagram:
untitled3na.png
 
simple test...feel it.

i can only speak for my zalman...but it pushes air toward the mobo.

i can tell my not feeling a breeze over it, but there is moving air coming out from the underside.

anyone who says otherwise doesnt have a HSF to actually feel the truth
wink.gif
 
Fans work by creating an area of low pressure, much like that on the wings of air planes. This principle states that air will move form an area of high pressure to low pressure, thus this is how we get "air flow." The fans do not in fact move in the direction you are drawing! They move toward the side where the blade is highest. If they moved in the direction that you are drawing theywould be operating in an extremely INEFFICIENT manner.
 
DSCF0211.jpg


in most cases the fans blow on to the motherboard, the reason for this is because alot of motherboard have passive north bridge and mosfet heatsinks, that require the airflow, static pressure is always lower with these fas as they are not desgined to suck, though some will produce better results in a suck config *if and only if * you have a spacer installed

thank you, you are wrong

thore
 
i always thought normal 80mm or 120mm fans take air away but the heatsink I believed brought cold air onto the CPU well im probably wrong :p
 
Oline61 said:
Very few people do this, it substantially increases temperatures over what most people run.
This is how your fan should work:
untitled4uw.gif
Click to expand...

umm, you even say yourself that this increases temps..... why would you want it to increase temps?.... i think your HSF is wired incorrectly.... every HSF i have owned(even the stock ones from intel and amd) blow down towards the mobo
 
The easiest test to see which direction a fan is blowing is to use a sheet of paper and if it gets sucked to the fan then it is blowing down on the MB, I'm sure you can figure out the opposite.
 
Just put a piece of paper onto my stock 3500+ HSF and it sucked it on! thus pushing air toward the Mobo.. thus inreturn pusing the cool air over the fins and cooling them and also pushing hot air out the sides...

Ok heres the question.. if you hsf was pulling air why would the HS itself get all dust clogged????
:D

Point proven i thinks
 
Oline61 said:
Very few people do this, it substantially increases temperatures over what most people run.
This is how your fan should work:
untitled4uw.gif


All of those Zalmans, the TT Big Typhoon, etc all pull air away from the mobo/heatsink.
Click to expand...

Wrong. I've owned both. Normal case/heatsink fans spin counterclockwise, and from all the blade diagrams you've shown us that would result in the fans BLOWING/PUSHING DOWN ON the heatsink, towards the motherboard. You should get a good understanding of things before trying to lecture about them.
 
You are asking for trouble if your Fan Pulls air instead of Pushing air onto the HS.
I have Been building PCs for 5 years now, and have yet to see a HS Pull air istead of pushing air.
 
and if there are no Croos points, then whats holding up the Fan????????...........Magic?
 
Oline61 really has no idea what he is saying. I'm not sure if he is doing it deliberatly or he just honestly does not understand what he is talking about. :confused: I mean this with the utmost respect, of course.
 
Fans push air onto a heatsink/chip.

While the exhaust from this blows warm air onto a mobo it means that cooler air, (away from the mobo, etc.) is blown onto the item being cooled. This maximizes the heat exchange. Since mobo typically run very much cooler than actively cooled chips this makes much more sense than drawing warm air from immediately above the mobo over a heatsink (the alternative).
 
What are you guy's talking about, fans dont push nor pull air, their there to support you in what you are doing :p ahhhh....bad bad joke. I think all that brick glue I was using for a flower bed killed my last 2 brain cells ;)
 
Oline61 said:
untitled6xq.png

Looking at the fan blades on any of these units, it is quite obvious which way air flows. It's not very complicated.

EDIT: To make it simpler, think of this. The air picks up heat going through the heat sink. If this heated air blew down, towards the motherboard it would increase temperatures, however if it blew out and away from the motherboard, it wouldn't. :D
Click to expand...


Oline61 said:
untitled5kb1.png
Click to expand...


LOLOLOLOLOLOLOL. Um, no. This is completely wrong. Do not listen to this person. The only thing he said that is true is this "Looking at the fan blades on any of these units, it is quite obvious which way air flows." Meaning, it is obvious that looking at those pics shows me that the fan blows downward, onto the heatsink/mobo.
 
I'm so glad other people finally started to correct Oline61 lol. I seriously hope he is kidding... :(
 
if your fan was wired wrong it would not spin at all. i think the only thing that is wired wrong here is Oline61. the only common application of a reversed heatsink fan i can think of is in 1U cases and the like. other than that its almost allways pushing at the heatsink.
o na side note... some people dont need BT's to come up with this kind of garbage, its just natural. i also love the "it would blow hot air into the heatsink increasing temps" line.... what the hell kind of preschool physics is that?
 
just try 1 way and see the temp flip it and see that temp i have run both ways my amd is pulling my intell is pushing but tryed both way on them and i got them set up the way the boxes wont
 
It's opposite day!!! "Happy opposite day, Patrick." "Thanks, Spongebob. I think the cyrix pr-133 is the greatest cpu ever!!! Just kidding it's OPPOSITE DAY!!! hahahahaha....."

......sigh :confused:
 
Seriously, that is so wrong its quite funny. If you just took a couple seconds to look at the fan when you switch off your pc you will clearly see which way it spins as its spinning down. Oline61 you're wrong on the fan shape as well.
 
OMG funniest thread I have ever seen in a while id say about 98% of fan on heatsinks blow onto the heatsink. There are only a few that ever did better pulling, e.g. Alpha coolers,swiftech coolers (air) and the XP120 and or XP90 where good in either direction it seemed. The fact is the fins have to be really close of pulling air out to work well.
 
Maybe he should stick his finger in an aluminum blade Tornado and see which side of his finger hurts the most.

Hope we didn't hurt his feelings, but you better know the facts before you argue a point.......if not, see what happens? :p
 
very weird
but to jump on the bandwagon
Stock A64 3200, the fan blows on the heatsink. The same with NB on my mortherboad
 
rich1111 said:
just try 1 way and see the temp flip it and see that temp i have run both ways my amd is pulling my intell is pushing but tryed both way on them and i got them set up the way the boxes wont
Click to expand...

This is what i do as well. In a really cramped case where the rear exhast fan is close to the cpu fan, it might be better to have air pulled over the cpu and then straight out of the back. My experience has been that athlon XPs preferred to be pulled, while my A64 likes to be pushed.

Oline's posts are great... to think he even used his leet photochop skills to demonstate as well....

 
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