sucks or blows, which is better?

[ric]

Unless you mounted a fan like in the example then that experience doesn't
apply.

What example? If you are referring to the one in
Message-ID: <[email protected]>, then I cannot say whether
or not that placement was tested since your description of "'hung in mid air'
at the front of the case" is too vague for me too be sure. If you had more
specifics maybe I could be more certain. As I said, fans were placed in
various relationships to the front panel, so maybe we *did* mount one like
your "example."

I said "for case cooling," not simply how to make a rear case fan run as if
it were mounted in free air, so my criteria would be more closely related
to airflow vs noise generated vs component cost and in light of what the
cooling requirements were and what other means for improving cooling might
be possible.

Well, since my input from the beginning of this thread basically was to
counter the suggestion that a front fan did no good. My very first post
in this thread was centered on the effect a front fan has on the rear
fans CFM. Noise & cost were not part of the OP's question, nor part of
my response.

Btw, just curious, do you know if the folks who ran the test used it on
production units?

Used *what* on production units?

The company sold cases, PSUs, fans, CPU HSFs, and a host of other aftermarket
computer accessories. The CFM tests were part of the design process of a new
series of cases. We were trying to determine the best fan placement areas in
the front and the rear. Three or four "models" of a full tower and of a mid
tower were built for these tests.

 

[JAD]

glad to see you guys know the In's and out's of sucking and
blowing.....

 

[David Maynard]

David Maynard wrote:




What example? If you are referring to the one in
Message-ID: <[email protected]>, then I cannot say whether
or not that placement was tested since your description of "'hung in mid air'
at the front of the case" is too vague for me too be sure. If you had more
specifics maybe I could be more certain. As I said, fans were placed in
various relationships to the front panel, so maybe we *did* mount one like
your "example."

If it isn't clear from my previous explanation of the exhaust air being
sucked back into the intake, and self neutralizing pressure zones, because
nothing separated the front of the fan from it's rear, I.E. no 'wall',
duct, flow director, panel, or anything else, then I doubt simply more
words will help much. As I said, "the fan was little more than simply 'hung
in mid air' at the front of the case. By that I mean, not flush against any
wall or other air director."

Well, since my input from the beginning of this thread basically was to
counter the suggestion that a front fan did no good. My very first post
in this thread was centered on the effect a front fan has on the rear
fans CFM. Noise & cost were not part of the OP's question, nor part of
my response.

The conversation progressed well beyond the 'beginning' a long time ago
and, at this point, I was postulating that rear fan RPM wasn't necessarily
the goal, that cooling was.

Used *what* on production units?

The test results. I was working under the assumption they didn't do them
simply because they were bored and was curious as to what, and how, they
applied them.

The company sold cases, PSUs, fans, CPU HSFs, and a host of other aftermarket
computer accessories. The CFM tests were part of the design process of a new
series of cases. We were trying to determine the best fan placement areas in
the front and the rear. Three or four "models" of a full tower and of a mid
tower were built for these tests.

oooooooooookedoke.

 

[ric]

If it isn't clear from my previous explanation of the exhaust air being
sucked back into the intake, and self neutralizing pressure zones, because
nothing separated the front of the fan from it's rear, I.E. no 'wall',
duct, flow director, panel, or anything else, then I doubt simply more
words will help much. As I said, "the fan was little more than simply 'hung
in mid air' at the front of the case. By that I mean, not flush against any
wall or other air director."

If you're relating a fan placement where 100% of the air pushed by the fan
circled around and re-entered the fan, then no - there was no placement
tested where this occurred. How much room was there between the fan and the
front of the case? 0.5"? 1"? More? Was this the case no matter the CFM rating
of the fan? What sort of obstruction appeared in *front* of the fan?

The test results. I was working under the assumption they didn't do them
simply because they were bored and was curious as to what, and how, they
applied them.

"Test results" is so much more descriptive than "it." Of course the results
of the test were incorporated into the case design. That was the purpose
of the tests.

 

[David Maynard]

David Maynard wrote:




If you're relating a fan placement where 100% of the air pushed by the fan
circled around and re-entered the fan,

Bingo. Close enough.

then no - there was no placement
tested where this occurred. How much room was there between the fan and the
front of the case? 0.5"? 1"? More? Was this the case no matter the CFM rating
of the fan? What sort of obstruction appeared in *front* of the fan?




"Test results" is so much more descriptive than "it." Of course the results
of the test were incorporated into the case design. That was the purpose
of the tests.

I'm glad it worked out but, as a heads up for future reference, you'll
eventually, and inevitably, run into a test where the results are negative.