A computer components & hardware forum. HardwareBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » HardwareBanter forum » General Hardware & Peripherals » General
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

PSU Fans



 
 
Thread Tools Display Modes
  #1  
Old February 11th 04, 01:02 AM
Muttly
external usenet poster
 
Posts: n/a
Default PSU Fans

Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1
points of the case, the other is inside the case pointing either up or down,
both fans are internal to the psu. My questions is which way should I have
the inside fan pointing? If it points up its got bout 4cm clearence between
it and the top of the case. If it points down its right over my cpu. For
better cooling which way do you think it should be pointing? If theres a
site or something that will give a good reason as to which way, a link would
be great. Better yet if someone has experience as to which way is best
that'd be great 2.
Thanks.
Martin.


  #2  
Old February 11th 04, 01:09 AM
philo
external usenet poster
 
Posts: n/a
Default


"Muttly" wrote in message
...
Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1
points of the case, the other is inside the case pointing either up or

down,
both fans are internal to the psu. My questions is which way should I have
the inside fan pointing? If it points up its got bout 4cm clearence


that's not going to be very good...
install it the other way around

between
it and the top of the case. If it points down its right over my cpu. For
better cooling which way do you think it should be pointing? If theres a
site or something that will give a good reason as to which way, a link

would
be great. Better yet if someone has experience as to which way is best
that'd be great 2.
Thanks.
Martin.




  #3  
Old February 11th 04, 01:21 AM
*Vanguard*
external usenet poster
 
Posts: n/a
Default

"Muttly" said in :
Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans.
1 points of the case, the other is inside the case pointing either up
or down, both fans are internal to the psu. My questions is which way
should I have the inside fan pointing? If it points up its got bout
4cm clearence between it and the top of the case. If it points down
its right over my cpu. For better cooling which way do you think it
should be pointing? If theres a site or something that will give a
good reason as to which way, a link would be great. Better yet if
someone has experience as to which way is best that'd be great 2.
Thanks.
Martin.


The fans must provide airflow in the *same* direction through the power
supply. Think about it: if you put 2 fans against each other but they were
blowing against each other (one blows at the other which blows back, or they
both try to suck away from each other), you get very little airflow (and
instead just get turbulence) unless the airflow for one fan is much higher
than the other and can overpower it.

The fan on the backside of the power supply should be blowing outward (i.e.,
from inside the power supply to the outside). The bottom fan should be
blowing into the power supply. That way the two fans are pulling or blowing
air through the power supply in the same direction (disregarding the bend of
the airflow from bottom to side).

From your description, is the bottom fan (which should be blowing upward and
into the power supply) actually on the *outside* of the power supply? It is
likely the power supply's case consume the standard volume as spec'ed for an
ATX power supply. That means the bottom fan being on the outside of the
power supply is extending beyond the volume set aside for the power supply
and intruding into the volume that would be assume usable by the motherboard
and any components sitting atop it.


--
__________________________________________________ __________
*** Post replies to newsgroup. E-mail is not accepted. ***
__________________________________________________ __________


  #4  
Old February 11th 04, 02:46 AM
Hank
external usenet poster
 
Posts: n/a
Default


"*Vanguard*" wrote in message
...
"Muttly" said in :

The fans must provide airflow in the *same* direction through the power
supply. Think about it: if you put 2 fans against each other but they

were
blowing against each other (one blows at the other which blows back, or

they
both try to suck away from each other), you get very little airflow (and
instead just get turbulence) unless the airflow for one fan is much higher
than the other and can overpower it.

The fan on the backside of the power supply should be blowing outward

(i.e.,
from inside the power supply to the outside). The bottom fan should be
blowing into the power supply. That way the two fans are pulling or

blowing
air through the power supply in the same direction (disregarding the bend

of
the airflow from bottom to side).

From your description, is the bottom fan (which should be blowing upward

and
into the power supply) actually on the *outside* of the power supply? It

is
likely the power supply's case consume the standard volume as spec'ed for

an
ATX power supply. That means the bottom fan being on the outside of the
power supply is extending beyond the volume set aside for the power supply
and intruding into the volume that would be assume usable by the

motherboard
and any components sitting atop it.


SAY WHAT?? What you been smokin?
Muttly, mount the friggin PSU like its supposed to be with the fan pointed
down. It aint nuclear science like some would like to make you believe.

Hank


  #5  
Old February 11th 04, 03:38 AM
kony
external usenet poster
 
Posts: n/a
Default

On Wed, 11 Feb 2004 01:02:53 -0000, "Muttly" wrote:

Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1
points of the case, the other is inside the case pointing either up or down,
both fans are internal to the psu. My questions is which way should I have
the inside fan pointing? If it points up its got bout 4cm clearence between
it and the top of the case. If it points down its right over my cpu. For
better cooling which way do you think it should be pointing? If theres a
site or something that will give a good reason as to which way, a link would
be great. Better yet if someone has experience as to which way is best
that'd be great 2.
Thanks.
Martin.


The fan should be facing down, blowing up, into the power supply.

This results in more air movement across the middle, more of the upper
left portion of the motherboard where heat-producing components like the
CPU, northbridge, and power regulation circuitry are located. There is no
need to move any air in-between the top of the power supply and the top of
the case, since there isn't anything there that produces heat. There are
exceptions, full tower cases that have hard drives mounted above the power
supply, but such cases have air vents or more fan mounts above the power
supply too, so the 2nd power supply fan should still be facing downwards.
  #6  
Old February 11th 04, 06:50 AM
~misfit~
external usenet poster
 
Posts: n/a
Default

Muttly wrote:
Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans.
1 points of the case, the other is inside the case pointing either up
or down, both fans are internal to the psu. My questions is which way
should I have the inside fan pointing? If it points up its got bout
4cm clearence between it and the top of the case. If it points down
its right over my cpu. For better cooling which way do you think it
should be pointing? If theres a site or something that will give a
good reason as to which way, a link would be great. Better yet if
someone has experience as to which way is best that'd be great 2.
Thanks.


Fan facing down. If you look you'll see that one of the PSU mounting screws
is off-set from the others. Let that be your guide.
--
~misfit~


  #7  
Old February 11th 04, 08:06 AM
Timothy Daniels
external usenet poster
 
Posts: n/a
Default

"Muttly" wrote:
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1
points of the case, the other is inside the case pointing either up or down,
both fans are internal to the psu. My questions is which way should I have
the inside fan pointing? If it points up its got bout 4cm clearence between
it and the top of the case. If it points down its right over my cpu. For
better cooling which way do you think it should be pointing? If theres a
site or something that will give a good reason as to which way, a link would
be great. Better yet if someone has experience as to which way is best
that'd be great 2.



The inside fan should be on the bottom of the power supply,
sucking air into the PSU. See the following webpage,
http://www.highpowersupply.com/produ...0102df.htm#2nd ,
and click on "Close-Up Pictures" and "Function of 2nd Fan".
It clearly shows that the bottom fan sucks air *into* the PSU,
away from the CPU heatsink, and the end fan blows air out of the
PSU and out of the case. Presumably, the airflow capacity of the
end fan is greater than that of the bottom fan so that air is drawn in
at the other end of the PSU, away from the optical drives and through
the PSU to the exterior of the case.

*TimDaniels*
  #8  
Old February 11th 04, 08:58 AM
Muttly
external usenet poster
 
Posts: n/a
Default

Thanks for the replies guys, I think I'll be pointing it downwards.
*Vanguard* as I said, both "both fans are internal to the psu".
Cheers.


  #9  
Old February 11th 04, 11:45 AM
Spajky®
external usenet poster
 
Posts: n/a
Default

On Wed, 11 Feb 2004 01:02:53 -0000, "Muttly" wrote:

My PSU (I can't remember the make or model, but its 550w) has 2 fans.


If it points up its got bout 4cm clearence between
it and the top of the case. If it points down its right over my cpu. For
better cooling which way do you think it should be pointing?


if the intake psu fan is right over Cpu fan, the Cpu fan should be
sucking air away from CPU (just opposite like usuall). Otherwise there
the Cpu temp & Psu one will increase because of dead
spot-underpresurized air between cpu fan & Psu intake fan!

-- Regards, SPAJKY ®
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
  #10  
Old February 11th 04, 02:33 PM
*Vanguard*
external usenet poster
 
Posts: n/a
Default

"Hank" said in .com:
"*Vanguard*" wrote in message
...
"Muttly" said in :

The fans must provide airflow in the *same* direction through the
power supply. Think about it: if you put 2 fans against each other
but they were blowing against each other (one blows at the other
which blows back, or they both try to suck away from each other),
you get very little airflow (and instead just get turbulence) unless
the airflow for one fan is much higher than the other and can
overpower it.

The fan on the backside of the power supply should be blowing
outward (i.e., from inside the power supply to the outside). The
bottom fan should be blowing into the power supply. That way the
two fans are pulling or blowing air through the power supply in the
same direction (disregarding the bend of the airflow from bottom to
side).

From your description, is the bottom fan (which should be blowing
upward and into the power supply) actually on the *outside* of the
power supply? It is likely the power supply's case consume the
standard volume as spec'ed for an ATX power supply. That means the
bottom fan being on the outside of the power supply is extending
beyond the volume set aside for the power supply and intruding into
the volume that would be assume usable by the motherboard and any
components sitting atop it.


SAY WHAT?? What you been smokin?
Muttly, mount the friggin PSU like its supposed to be with the fan
pointed down. It aint nuclear science like some would like to make
you believe.

Hank


It all depends on which ATX specification the power supply follows. In ATX
pre-2.2 power supplies, the air flow was INTO the case at the rear panel so
air flow was INTO the power supply's opening on the backside of the case;
i.e., the power supply's rear opening was an air inlet. This contradicted
the earlier AT spec which had air flow move out of the case as an exhaust
port. ATX 2.2 reversed the air flow and now, like the AT spec, has airflow
move OUT of the power supply at the rear panel. So for the power supply
opening at the rear of the case:

- For an AT power supply, air flow is OUT of the case.
- For an ATX pre-2.2 power supply, preferred air flow is INTO the case.
- For an ATX 2.2 power supply, preferred air flow is OUT of the case.

ATX 2.01 Specification (released 1996), Section 4
ftp://download.intel.com/design/motherbd/atx_201.pdf
ATX 2.03 Specification (released 1997), Section 4
http://ulita.ms.mff.cuni.cz/pub/techdoc/atx/atx2_03.pdf
"The 'preferred' airflow solution is to pull air through the power supply
from outside the chassis and direct it onto the processor. However, other
solutions may be implemented to meet the specific cooling requirements."

ATX 2.1 Specification
http://www.formfactors.org/developer...s%5Catx2_1.pdf
This spec doesn't say anything about airflow direction for the power supply.
There is the implication that airflow is the same as in the prior specs per
Section 5.1, "Venting", where it says, "Adequate venting should be provided
in the system to allow for unimpeded and well-designed airflow to cool key
components such as the processor." But airflow in either direction across
the processor would assist removal of the warmed air from the processor
(although a PSU that exhausts air across the processor may be doing so with
pre-warmed air taken into the PSU through its internal-side vents).

ATX12V 2.2 Specification, Section 4.3
http://www.formfactors.org/developer...20Ratified.pdf
"In general, exhausting air from the system chassis enclosure via a power
supply fan at the rear panel is the preferred, most common, and most widely
applicable system-level airflow solution."

The ATX specification as regards to the direction of airflow through the
power supply are only recommendations (i.e., they are ambiguous). As such,
you have to test your power supply to see which direction is its airflow. I
picked up a Fortron 350W PSU about 2 months ago which has 2 fans. The
bottom fan is an inlet port (air goes INTO the power supply) and the rear
fan is an exhaust port (air goes OUT of the power supply). So my power
supply is ATX12V 2.2 compliant, and the fans work in concert to pass air
*through* the power supply instead of working against each other. The
bottom fan is primarily a backup in case the rear fan stops spinning or
spins too slowly (especially for rear fans with manual speed adjust).
Sometimes the rear fan is temperature controlled but the bottom fan is
usually fixed speed (because it is the backup or to ensure a minimal flow
rate).

2 equally strong guys push against opposite sides of a crate. The crate
doesn't move. The same 2 equally strong guys pull against opposite sides of
a crate. The crate still doesn't move. 2 guys of different strengths push
against opposite sides of a crate. The crate moves slowly in the direction
of the weaker guy. 2 guys of different strengths pull against opposite
sides of a crate. The crate move slowly in the direction of the stronger
guy. 2 guys of equal or unequal strength either both push or pull against
the crate in the same direction. The crate moves fastest in that direction
because the guys work together instead of opposing each other. Fans provide
the force. Air has mass and momentum, too. Hank never took physics in high
school, or he failed, or he skipped that class or high school altogether.


If the ATX power supply has the *optional* cooling vents on the inside
(where the wire harness exits), the fans could both be pushing air out of
the power supply; i.e., the rear fan would exhaust out of the case and the
bottom fan would exhaust out across the processor. That is because you now
have an alternate path for airflow other than through the openings for the
fans. However, realize that the vent openings on the internal side of the
power supply are rarely sufficient in their cumulative size to accomodate
the same [potential] airflow provided by just one of the fans. Also realize
that the bottom fan would then be recirculating the pre-warmed air from
inside the case across the processor. So despite if there are vents or not,
you want to either move the cold air in or the warmed out. You don't want
to be sucking the air that has already been warmed by the hard drives,
expansion cards, RAM sticks, and processor into the power supply's inlet
vents to only then get recirculate that pre-warmed air back over the
processor.

Your CPU probably has its own fan. Figure out which way the rear fan in the
power supply is directing airflow, then make the bottom fan on the power
supply move the air in the same direction so it assists with airflow rather
than opposes it.

--
__________________________________________________ __________
*** Post replies to newsgroup. E-mail is not accepted. ***
__________________________________________________ __________


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
intel board, fans on during standby. intel d875PBZ. JohnJ General 0 January 13th 04 05:14 PM
Case Fans which way in or out [email protected] General 17 November 23rd 03 10:13 AM
Faulty fans: dust or bearings? S.Boardman General 37 October 16th 03 10:34 AM
Silent Computer - Advice David Taylor General 49 October 7th 03 11:26 AM
Sleeve bearing fans Adrian General 6 August 2nd 03 01:14 AM


All times are GMT +1. The time now is 05:59 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright ©2004-2022 HardwareBanter.
The comments are property of their posters.