Hi

This is a question regarding the directions of air currents in the pc. I
discovered that both the power supply fan and the fan attached to the case of
my pc were blowing air outwards, as a result the fan on my processor was
working overtime to keep things cool and at the same time making my pc very
noisy. I decided to change the direction of the fan attached to the case so
that it now blows air into to pc.
Was this the correct thing to do, or will it damage my pc?

On which side of the case ( Intake or Exhaust ) ?

Airflow ( <> ) needs to be balanced, so that neither the
exhaust or intake is significantly greater than the other.
Cabling makes a big impact, especially the 40/80-pin IDE
cables and also the non-connected power taps. Most fans
generate 18db of noise so there is a point where too many
fans, rotating at maximum speed mimics a "Wind Tunnel"
What you should do is install a program like SpeedFan to
monitor your Motherboard/CPU sensors and detect the
% of max your fans are rotating at.

Newer cases have a direct vent from CPU fans to the left
side panel of the case.

For example, the following would be a fully configured fan
setup ( Not really practical for average Desktop PCs ).

<--PS
CPU^
Northbridge ( Passive )
Southbridge ( Passive )

<-Case Exhaust
Drive Cage Intake <-
Case Intake <-
Video Card ^



"Tom" <(E-Mail Removed)> wrote in message
news:FB5C325C-C0D4-4B04-8C10-(E-Mail Removed)...
> Hi
>
> This is a question regarding the directions of air currents in the pc. I
> discovered that both the power supply fan and the fan attached to the case
> of
> my pc were blowing air outwards, as a result the fan on my processor was
> working overtime to keep things cool and at the same time making my pc
> very
> noisy. I decided to change the direction of the fan attached to the case
> so
> that it now blows air into to pc.
> Was this the correct thing to do, or will it damage my pc?

Tom wrote:
> Hi
>
> This is a question regarding the directions of air currents in the
> pc. I discovered that both the power supply fan and the fan attached
> to the case of my pc were blowing air outwards, as a result the fan
> on my processor was working overtime to keep things cool and at the
> same time making my pc very noisy. I decided to change the direction
> of the fan attached to the case so that it now blows air into to pc.
> Was this the correct thing to do, or will it damage my pc?

If you think about it, the same volume if air is moved into or out of the
computer regardless of which way the fan pushes it. The difference is the
path the air takes. Case fans are designed for the best air flow for what
they have to cool but more importantly, when blowing OUT, they blow dust,
etc., out of the case in the air stream where the other way around the dust
is blown IN, probably directly onto the hottest components, which will cause
things to heat up faster.

Damage? Probably not, but it can't be determined. It IS against the
accepted design standard for that houseing, though.

Tom wrote:
> Hi
>
> This is a question regarding the directions of air currents in the pc. I
> discovered that both the power supply fan and the fan attached to the case of
> my pc were blowing air outwards, as a result the fan on my processor was
> working overtime to keep things cool and at the same time making my pc very
> noisy. I decided to change the direction of the fan attached to the case so
> that it now blows air into to pc.
> Was this the correct thing to do, or will it damage my pc?

The intake vents draw cool air into the case, across the components,
upward where heat flows naturally, then out the fans. Reversing a fan
would tend to increase the pressure in the case (no big deal), but would
certainly change the designed airflow across the components..

--
Joe =o)

A well designed case will come with all the fans it needs and they will
already be installed correctly. With most cases you may have to experiment.
Download a program that will give you an indication of CPU temps. SpeedFan
is as good as any. Without a digital thermometer all you are getting is an
indication but that will be good enough for now. Start the computer and
perform a test that you can duplicate. e.g. open and close a number of
programs, play a game demo, etc.. The test should last for at least ten
minutes with constant activity all the time. This activity should include
graphics and reading the hard drive as these activities will significantly
increase temperatures inside the case. Monitor the temperatures. Shut down
the computer and reverse the fan. Perform the same exact test again and
monitor the temperatures. The results should be obvious. With some cases you
will see a dramatic difference. With others it may make very little
difference. This only takes into account CPU temperatures. There are other
temperatures that you should also be concerned about. SpeedFan will also
monitor hard drive temperatures. If you have a discrete graphics card you
may also want to find a utility to monitor it's temperature as well.

http://www.almico.com/speedfan.php

--
Kerry
MS-MVP Windows - Shell/User
http://www.vistahelp.ca


Tom wrote:
> Hi
>
> This is a question regarding the directions of air currents in the
> pc. I discovered that both the power supply fan and the fan attached
> to the case of my pc were blowing air outwards, as a result the fan
> on my processor was working overtime to keep things cool and at the
> same time making my pc very noisy. I decided to change the direction
> of the fan attached to the case so that it now blows air into to pc.
> Was this the correct thing to do, or will it damage my pc?

Tom wrote:

> This is a question regarding the directions of air currents in the
> pc. I discovered that both the power supply fan and the fan attached
> to the case of my pc were blowing air outwards,


That's perfectly normal and if not quite universal, very common.


> as a result the fan
> on my processor was working overtime to keep things cool and at the


I doubt that very much.


> same time making my pc very noisy. I decided to change the direction
> of the fan attached to the case so that it now blows air into to pc.
> Was this the correct thing to do, or will it damage my pc?


Cases are designed for fans to blow in a particular direction, and the case
is cooled most efficiently when the fan is installed as it was designed to
be. Unless it was misinstalled in the first place (which is probably
unlikely) if you have changed the direction of air flow, you are probably
getting inadequate cooling, and yes, that could damage the computer.

--
Ken Blake - Microsoft MVP Windows: Shell/User
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