CPU fan question

It is normal to blow air onto the heatsink - if you want to cool anything
down to you blow onto it or try to blow the hot air away?

I don't recall ever using a cooling fan which blew hot air away from the
heatsink, and i've been building PC's for years.....although I imagine they
do exist out there.

"Ken_B" <@> wrote in message news:10634gb5j0gp5ff@corp.supernews.com...
 > Hi. I recently got a new Abit VA-10 m-board and my first Athlon (2500+)
CPU.
 >
 > I just noticed that the CPU fan (designed for the 2500+, according to the
 > local computer shop where I bought it) seems to blow air down toward the
 > heat sink rather than sucking it away, as every other cooling fan I have
 > ever used.
 >
 > Is this normal for Athlon cooling fans? The temperature of the CPU hovers
 > around 127 degrees, according to Hardware Doctor.
 >
 > Thanks.
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

 >I don't recall ever using a cooling fan which blew hot air away from the
 >heatsink, and i've been building PC's for years.....although I imagine they
 >do exist out there.

They exist. Some older high quality Alpha heatsinks had the fan blowing away
from the heatsink. The heatsink was covered with a shroud and with a little bit
of open space to let the air at the bottom. There might also be some newer
models that also work with the fan blowing away.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

I am currently using my 80mm Mechatronics HS fan to "suck" the air up
through the Swiftech heatsink, through an elbow shroud, and exiting towards
my 80mm exhaust case fan.

I also have 2 Adda 80mm fans in the lower front of the case.

Works fine and I get about 37c w/ ambient of 26c

--
Ron Marraccini

1964" <private1964.RemoveThis@aol.com> wrote in message
news:20040324120647.03906.00000025@mb-m29.aol.com...
  > >I don't recall ever using a cooling fan which blew hot air away from the
  > >heatsink, and i've been building PC's for years.....although I imagine
they
  > >do exist out there.
 >
 > They exist. Some older high quality Alpha heatsinks had the fan blowing
away
 > from the heatsink. The heatsink was covered with a shroud and with a
little bit
 > of open space to let the air at the bottom. There might also be some newer
 > models that also work with the fan blowing away.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

 >I am currently using my 80mm Mechatronics HS fan to "suck" the air up
 >through the Swiftech heatsink, through an elbow shroud, and exiting towards
 >my 80mm exhaust case fan.


I think the only time it might be better is if there is a shroud of some kind
around the heatsink.
In your case It might better to run a duct from the side to the fan blowing on
the heatsink. That way the rear exhaust fan can also be helping to cool the
case temp as well.
There is never one sure answer to what's right and whats wrong with cooling.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

The most significant element in your question is the ref to 127 !
Are you sure ? 127 C is kinda hot
Are you reading Hardware Doctor right ?

Denis







"Ken_B" <@> wrote in message news:10634gb5j0gp5ff@corp.supernews.com...
 > Hi. I recently got a new Abit VA-10 m-board and my first Athlon (2500+)
CPU.
 >
 > I just noticed that the CPU fan (designed for the 2500+, according to the
 > local computer shop where I bought it) seems to blow air down toward the
 > heat sink rather than sucking it away, as every other cooling fan I have
 > ever used.
 >
 > Is this normal for Athlon cooling fans? The temperature of the CPU hovers
 > around 127 degrees, according to Hardware Doctor.
 >
 > Thanks.
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

 >Are you sure ? 127 C is kinda hot

It must be Farenheit<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

On 24 Mar 2004 22:08:18 GMT, private1964 RemoveThis @aol.com (PRIVATE1964) wrote:

  >>Are you sure ? 127 C is kinda hot
 >
 >It must be Farenheit

Yes, it is. Water boils at 100c.
127f is about 53c. That's a bit high for idle temp. Unless it's a
Prescott. <!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

I always though it better to suck hot air out the top rather than blow it
out the bottom. I could be wrong.

In my case, there is a second power supply fan right next to the CPU which
sucks air away from the CPU and out the back of the supply. Seems to be
fighting the CPU fan, blowing in another direction.

Someone suggested trying it both ways: but how would you reverse the
flow???? Surgery on the wiring?

About the temperature: the computer has been running about 10 hours today,
at the 18mHz CPU is steady at 153 degrees F. Does that sound OK??

Thanks for all the replies.

Ken

"Slug" <slug.DeleteThis@no_email.here> wrote in message
news:b554609bb9fgso3h1a1clmleu5ih4id545@4ax.com...
 > On 24 Mar 2004 22:08:18 GMT, private1964.DeleteThis@aol.com (PRIVATE1964) wrote:
 >
   > >>Are you sure ? 127 C is kinda hot
  > >
  > >It must be Farenheit
 >
 > Yes, it is. Water boils at 100c.
 > 127f is about 53c. That's a bit high for idle temp. Unless it's a
 > Prescott. <!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

On Wed, 24 Mar 2004 18:07:54 -0600, "Ken_B" <@> wrote:

 >I always though it better to suck hot air out the top rather than blow it
 >out the bottom. I could be wrong.

Top rear case fans is for that. The cpu fan is to cool off the
heatsinsk itself by blowing cooler air directly on it. I have seen the
reverse done too though but I don't know which is more efficient.
I would try yours blowing onto the cpu.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

 >I always though it better to suck hot air out the top rather than blow it
 >out the bottom. I could be wrong.

It depends how the heatsink was designed, but most heatsinks blow air into the
heatsink.
If you want to try the other way, you just take the fan off and flip it the
other way. You don't need to re-wire the fan.
If you look at the side of the fan most have 2 arrows on them. The arrows tell
you which way the fan spins, and which direction the air flows out of the fan.
Just flip the fan over.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

I plugged in a couple of spare socket 370 cooler fans, and you are right. I
could tell they were blowing in toward the heat sink. But if you hold your
fingers close to the fan, if feels as if they are blowing out. So I was
confused (which isn't rare). Thanks.


"PRIVATE1964" <private1964 DeleteThis @aol.com> wrote in message
news:20040324200511.19539.00000055@mb-m20.aol.com...
  > >I always though it better to suck hot air out the top rather than blow it
  > >out the bottom. I could be wrong.
 >
 > It depends how the heatsink was designed, but most heatsinks blow air
into the
 > heatsink.
 > If you want to try the other way, you just take the fan off and flip it
the
 > other way. You don't need to re-wire the fan.
 > If you look at the side of the fan most have 2 arrows on them. The arrows
tell
 > you which way the fan spins, and which direction the air flows out of the
fan.
 > Just flip the fan over.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

 > Top rear case fans is for that. The cpu fan is to cool off the
 > heatsinsk itself by blowing cooler air directly on it. I have seen the
 > reverse done too though but I don't know which is more efficient.
 > I would try yours blowing onto the cpu.

While at it, my case have 2 rear exhaust fans in vertical config. The edge
of fan1 (on top of fan 2) is almost touching the edge of heatsink fan on
Spire WhisperRock4 (80mm fan as well), in kinda like this |_ while cpu
heatsink being at bottom..
Oh and heatsink fan blows air ONTO heatsink, not suck away.

While the fan2 is about 2cm below the cpu heatsink, blowing air out.

So do I get better result if I reverse the topmost rear exhaust fan, so it
blows air inside the chassis, and right onto the Spire WhisperRock4 to cool
cpu, rather than blowing out and creating a vacuum above heatsink?
This -vacuum- makes WhisperRock4 run on 2800-2900rpm, while it's supposed to
run at 2500. If I disable fan1, then rpm drops to 2550-2590, and I notice
only 2-4C increase in cpu temp.

Any suggestions on how to adjust any of these 3 fans??<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question 

On Thu, 25 Mar 2004 16:55:51 GMT, "Asestar" <a s e s t a r @ s t a r t
.. n o> wrote:


 >While at it, my case have 2 rear exhaust fans in vertical config. The edge
 >of fan1 (on top of fan 2) is almost touching the edge of heatsink fan on
 >Spire WhisperRock4 (80mm fan as well), in kinda like this |_ while cpu
 >heatsink being at bottom..
 >Oh and heatsink fan blows air ONTO heatsink, not suck away.
 >
 >While the fan2 is about 2cm below the cpu heatsink, blowing air out.
 >
 >So do I get better result if I reverse the topmost rear exhaust fan, so it
 >blows air inside the chassis, and right onto the Spire WhisperRock4 to cool
 >cpu, rather than blowing out and creating a vacuum above heatsink?
 >This -vacuum- makes WhisperRock4 run on 2800-2900rpm, while it's supposed to
 >run at 2500. If I disable fan1, then rpm drops to 2550-2590, and I notice
 >only 2-4C increase in cpu temp.
 >
 >Any suggestions on how to adjust any of these 3 fans??
 >

I only use one rear case fan on both my PC's and both are used to
exhaust heat. My Antec case has four slots for case fans, two front
and two rear but I just use the one rear case fan and find that
sufficient. I'm trying to keep the noise down and only use what is
necessary. I suggest you try just using one rear exhaust case fan and
see how it goes. Maybe move the extra fan to the front to bring air
in, but if you do that try to fit some type of filter to lessen the
dust it sucks in with it.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: CPU fan question