Can AC fans be used inside cases?

[w_tom]

Well then put up some numbers from your machine and we shall
see how many fans are necessary. Your keyboard does have
numbers on it?

 

[David Maynard]

Your numbers then say only one chassis fan is required. But then a
simple calculation demonstrates what most every system requires.

Don't insult others by bottom posting to make posts difficult to read.
Wading through old and now irrelevant information is both intentionally
and obviously wasteful. Or learn what top poster do - be tolerant of
the intolerant - and ignore their misguided bottom posting.

RFC 1855
(quote)
If you are sending a reply to a message or a posting be sure you
summarize the original at the top of the message, or include just
enough text of the original to give a context.
(/quote)



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http://www.netmeister.org/news/learn2quote2.html -- Netmeister: "How do I
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http://mailformat.dan.info/quoting/ -- Dan's Mail Format Site: Quoting,
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<snip>

 

[Lordy]

Sometimes memory is defective.

I was prepared to follow your argument until you sidestepped with this.

The issue at hand is


1. Does hardware last longer with better cooling? Yes/No?

2. Do all variations of "home" computers just need two fans for adequate
cooling? Yes/No? (Take into account Owners environment eg Tropics + amount
of equipment stuffed into one box)

If you can answer yes or no to both of the above questions without going
off on a tangent I will be pleasantly surprised?

PS Why are server rooms so cold?

 

[Lordy]

Don't insult others by bottom posting to make posts
difficult to read.

QED.

 

[Odie Ferrous]

1. Heat dramatically reduces the life span of most components found
within a computer.
2. Stop detracting from 1. above.
3. You have no further constructive arguments, and are now trolling.
4. See 1. above. Read it 10 times.



Odie

 

[hona ponape]

(e-mail address removed) (do_not_spam_me) :

Right, unless the case fans are set up wrong (blowing in the wrong
direction) or are too small (5" may be needed) or the system is
overclocked. The only additional need may be a duct to bring outside
air to CPU fan.

What if it is not a home computer? Some people use computers to do things
other than play games and post stupid messages on the internet.

To the original poster, I have used AC fans and have not had a problem.
However due to the 'unusual' configurations, I cannot say that they will
work for you.

 

[SteveH]

Well then put up some numbers from your machine and we shall
see how many fans are necessary. Your keyboard does have
numbers on it?

And as I said above, what numbers are you you talking about? I presume you
can read?

SteveH

 

[Andy]

I have several Panaflow AC fans, powerful and quiet. Is there any
reason these could not be used inside a case? I realize the power
supply could not be used, so I'd have to tap in the power supply or
run a separate power line into the case. Has anyone tried this?

They will work just fine.

Below article may help

http://www.dansdata.com/hx45fan.htm

Andy

 

[w_tom]

IC life expectancy is shortened by higher temperature
operation. Equations for shortened life expectancy could be
provided (Odie Ferrous' response stops here). Then we apply
numbers to those equations. Life expectancy of a transistor
at 150 or 200 years might be massively lowered - to 100
years. IOW irrelevant.

Maximum temperature is more about keeping it cool enough so
that parameters such as timings remain within 'operational
limits'. Those temperatures do not approach destructive
temperatures.

Even from those early days when an audio op amp burned
figures in the 1960s - its not too hot as long as it does not
leave skin. Background experience provided for comprehension
of the answer.

The first answer is both yes, higher heat shortens the life
expectancy AND no, the shortened life expectancy is completely
irrelevant.

In another discussion on chassis fans where numbers were
posted by many, one 80 mm fan of about 30 CFM was demonstrated
sufficient to cool a whole system powered by a 350 watt power
supply in a 100 degree room. As I recall, a second fan only
reduced chassis temperatures by a totally irrelevant 5
degrees. Third fan provides even less improvement.
Completely irrelevant improvements especially if system must
also work with sufficient margin when room temperatures exceed
100 degree F.

One chassis fan is sufficient for most every system. Two
placed in series (one blowing out and the other sucking in)
provide redundancy - increased system reliability - when
mechanical fans tend to be a higher failure device.

Footnotes - a chassis layout must take care that no hotspots
exist. Ribbon cable placement is critical. Therefore some
chassis fans are placed to also eliminate the hot spots. One
80 mm fan is typically sufficient in a system design that does
not even consider additional cooling from the metal chassis
cover.

Why are server rooms so cool? A stuck fan does not crash
the server. Furthermore, in the early days, computer room
components sometimes did not work even with modest temperature
increase - no matter what the specs said. For example, we had
a whole room full of Perkin Elmers all go down exactly at a
room temperature of 78 degrees. Another server room computer
(Gould) would fail at 72 degrees. Their temperature
dependency was accurate enough to calibrate a thermometer.
Therefore legacy experience says always run a computer room
with coldest air under the floor blowing into every machine.

Back then, numerous computers did not even meet temperature
specs. Fans failed frequently. A cold room avoided both
problems. So yes, run a room full of servers in a cooler room
anyway. It makes tightly packed systems less susceptible to
crashes from high failure devices such as fans. PCs don't have
anywhere near the reliability requirements nor the tight
packaging found in servers.

Server room temperature is not relevant to PC fans. Again,
look at the numbers. Add more fans (in parallel) and how much
more cooling does one get? Insignificant. Too many fans
creates other problems - ie excessive dust.

 

[w_tom]

Numbers that involve heat are required. Things like thermal
conductivity, energy consumption, fan parameters, etc. All
numbers that relate system operation and heat - as is the
topic.

 

[SteveH]

Numbers that involve heat are required. Things like thermal
conductivity, energy consumption, fan parameters, etc. All
numbers that relate system operation and heat - as is the
topic.

I don't need to know all of those things to easily see that if I turn down
all my four case fans (two sucking, two blowing) to their minimum, the CPU
temperature goes up by about 10c, which on an Athlon when working hard,
pushes it to the point where it starts to go flaky.
And yes, I have tried connecting/disconnecting various combinations of these
fans and have found out that what I have now works best for MY pc.

I have built plenty of PC's that have only needed two fans, but they also
have had slower CPU's, one HDD and one optical drive, and therefore generate
way less heat than all of the kit in my PC.

SteveH

 

[Phisherman]

They will work just fine.

Below article may help

http://www.dansdata.com/hx45fan.htm

Andy

Good hands-on article. Thanks Andy. I plan on using gauge #14 Romex
wire with a fuse in the connection box.

 

[Guest]

On Mon, 06 Dec 2004 16:58:42 +0100, "(e-mail address removed)"


I have several Panaflow AC fans, powerful and quiet. Is there any
reason these could not be used inside a case?

Good hands-on article. Thanks Andy. I plan on using gauge #14 Romex
wire with a fuse in the connection box.

#14 Romex is not only overkill for just fans but also may be less safe
than other wiring because of the connections. You'll get the nicest
setup with an IEC type power entry receptacle consisting of an on-off
switch, power cord receptacle, and fuse holder in a single package,
such as one of these: www.mouser.com/catalog/620/708.pdf. But you may
find it cheaper to just buy a separate receptacle, switch, and fuse
holder.

 

[w_tom]

These posts on chassis fans were provided for other's
benefit. Four fans is woefully excessive noise, wasted money,
and creates a chassis dust problem. A properly cooled
computer in any typical room should never require the constant
dust cleaning created by too many fans.

Again, for the benefit of others. Some will absolutely
insist they know facts. When they have to provide numbers,
they cannot. No numbers is sufficient to suspect junk science
reasoning.

Too often, more fans cure symptoms of defective hardware
rather than replace that hardware. Moreso, that defective
hardware may just fail months or a few years later; after
warranty expires. Others who have done the numbers and
demonstrated same by experimental example (principles that are
taught in junior high school science) have posted one 80 mm
fan of about 30 CFM is more than sufficient to cool most every
computer chassis. Don't get caught up in the myth of 'more
fans'. If one fan is not sufficient, find and fix the reason
problem.

Steve says he turns down fans and his CPU gets 10 degrees
hotter. But he does not list how many CFMs reduced. Did he
slow those fans to a total of 10 CFM? Of course the CPU got
hotter. Again, he fails to provide any numbers. Therefore we
learn nothing relevant. Even listing the chassis interior
temperatures could have provided more useful facts. No numbers
is too common with the myths of junk science reasoning.

 

[Andy]

Good hands-on article. Thanks Andy. I plan on using gauge #14 Romex
wire with a fuse in the connection box.

Glad it helps, I am from UK so not really used to the AWG sizes, I would
use something in the 0.2mm stranded range suitable for lighting with a
rating of 3amps at 240v.

Agreed about the fuse, no harm in that at all.

Andy

 

[SteveH]

These posts on chassis fans were provided for other's
benefit. Four fans is woefully excessive noise, wasted money,

Not if you have quiet fans to start, and you can regulate the speed.

and creates a chassis dust problem. A properly cooled
computer in any typical room should never require the constant
dust cleaning created by too many fans.

Not if you have the intake fans filtered, as they are in my PC case (have a
look at a Thermaltake Xaser III)

Again, for the benefit of others. Some will absolutely
insist they know facts. When they have to provide numbers,
they cannot. No numbers is sufficient to suspect junk science
reasoning.

Too often, more fans cure symptoms of defective hardware
rather than replace that hardware. Moreso, that defective
hardware may just fail months or a few years later; after
warranty expires. <snip>

In my case it has nothing at all to do with defective hardware. The memory
passes extensive testing with Memtest, the HDD's pass their fitness tests as
does any other part that I can reasonably test WITHOUT wasting hours testing
each part down to component level.

Steve says he turns down fans and his CPU gets 10 degrees
hotter. But he does not list how many CFMs reduced. Did he
slow those fans to a total of 10 CFM? Of course the CPU got
hotter. Again, he fails to provide any numbers. Therefore we
learn nothing relevant. Even listing the chassis interior
temperatures could have provided more useful facts. No numbers
is too common with the myths of junk science reasoning.

You don't listen to others, do you? I stated in my previous reply that I
have built plenty of PC's with only two fans. I even accept the fact that
its perfectly possible to build a PC with no fans, provided the box isn't
full of heat generating extra parts, like mine is.
As I said, with one HDD, one optical, non-overclocked CPU and memory and an
average video card, your one or two fans theory, is perfectly possible, but
in my PC it isn't because of all the extra (heat generating parts) parts.
And I don't need science to tell me what I can clearly see for myself.
But my main point still stands - you can't just genralise on these things
the way you originally did. Every case is different.

SteveH

 

[David Maynard]

Not if you have quiet fans to start, and you can regulate the speed.




Not if you have the intake fans filtered, as they are in my PC case (have a
look at a Thermaltake Xaser III)




In my case it has nothing at all to do with defective hardware. The memory
passes extensive testing with Memtest, the HDD's pass their fitness tests as
does any other part that I can reasonably test WITHOUT wasting hours testing
each part down to component level.




You don't listen to others, do you? I stated in my previous reply that I
have built plenty of PC's with only two fans. I even accept the fact that
its perfectly possible to build a PC with no fans, provided the box isn't
full of heat generating extra parts, like mine is.
As I said, with one HDD, one optical, non-overclocked CPU and memory and an
average video card, your one or two fans theory, is perfectly possible, but
in my PC it isn't because of all the extra (heat generating parts) parts.
And I don't need science to tell me what I can clearly see for myself.
But my main point still stands - you can't just genralise on these things
the way you originally did. Every case is different.

Well, actually, you can 'generalize' but you're also correct that each case
is different.

Case cooling is the thermal capacity of the cooling medium (air) and how
much of it to move based on how much temperature rise you want.

So, in basic theory (ignoring lower order altitude and temp variations)

Delta-C = 1.71 * Watts/CFM (for air)

And I would imagine that's the origins of where w_tom is coming up with his
25-30 CFM 80mm fan although, while he constantly pontificates about
'engineering' and 'numbers', he rarely provides anything, in that regard,
of much practical use, like the actual equation.

However, you will notice right off that there are two assumptions in there:
the desired case temp rise and the total power being dissipated in the case.

Things not obvious from the equation are that, for one, and depending on a
host of case factors, you'll likely get less than half the rated CFM from a
case fan in actual, mounted, use. So, if you need 25 CFM, a 25 CFM fan
isn't going to do it and you'd be looking at a 50 CFM fan (if you're doing
positive case pressure filtered intake you can forget getting anywhere near
50% even before taking into account filter clogging over the maintenance
interval). Second, the equation presumes an even temperature across the
case and uniform airflow through it; neither of which will be reality.

To make matters worse, CPU heatsink fans can act as a 'stirrer', in
addition to cooling the heatsink, and dilute the case fan's effect because
the warmer HSF air is constantly remixed with the incoming case airflow.
That effect is minor with a small HSF, as with older low power processors,
but can become significant when the HSF's volume is nearly as large as the
case fan's. Regardless, the air temperature around the processor, and other
'high power' components, is going to be higher than the 'calculation' case
temp even before one considers uneven case airflow distribution.

Another factor missing from the equation is just how much noise you are
willing to live with and (if we're looking for 25 CFM total) two 25 CFM
fans are quieter than a single 50CFM fan of the same size. Or one could
change to a larger diameter fan, IF the case can support a larger diameter fan.

The long and short of it is, while the 'theory' may say 25 CFM is enough,
depending on a number of variable assumptions, reality can be quite different.

In addition to 'high power' component cooling, which is needed simply to
get their heat into the case air, you can end up with hotspots (case
airflow inconsistencies) necessitating additional localized cooling and
more than one exhaust fan may be desirable from a CFM/noise aspect above
and beyond the raw 'horsepower' to get the needed CFM. And intake fans may
be desirable to direct inlet airflow to a particular portion of the frontal
area, such as over hard drives.

And then there's the fact that it's easier to approach 'theoretical' when
one can design their own case but when putting fans in an existing case
you're often stuck with whatever 'inefficiencies' the case designer built
into it and adding a second exhaust fan is more practical than trying to
reverse engineer case airflow directors/ducting.

So, 'everybody' is 'right'. In theory, given complete design freedom and no
restricting criteria, such as noise, fan size, etc., one can cool a
'typical' PC with one case fan. However, give the particulars of a specific
PC it may be quite desirable to have more than one.

Having said that, there does seem to be a tendency for some home builders
to 'over fan' their cases for little benefit.

 

[Matt]

Don't insult others by bottom posting to make posts
difficult to read. Wading through old and now irrelevant
information is both intentionally and obviously wasteful. Or
learn what top poster do - be tolerant of the intolerant - and
ignore their misguided bottom posting.

A: Because it ruins the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

 

[datawraith3080]

You worry too much. I know this is a dead thread, but I feel completeness of information is beneficial

AC powered fans are better, they simply are. They move more air with less noise, and what noise they produce is a pleasant low whir opposed to the awful screech of DC fans. My gaming computer currently uses 5 Howard Industries CYCLOHM fans.

Secondly, people don't think. It is very easy to solder leads off of the power input of your PSU for ac fans. If you can use a soldering iron, this is no issue. Also, note that the case is already grounded, if you use a three prong cable. Just ensure you keep polarity right.

Third. my fans all turn on with the computer, because I have a 12 volt automotive relay hooked up to the power supply. As complex solutions go, this isn't one of them. It is quite reliable actually.

Automotive relays are cheap, work very well, have high power-handling capabilities, and can fit easily within the PSU case. Want one? Go to autozone and spend... oh three dollars or so. Put a fuse inline with the fans if you are so inclined. Then, simply mount a connector of some sort to the PSU for the ac fans and wire them up.

Fans are insulated by the way. No need to go crazy with nylon or anything of that order. Really... it just does not happen.

Worrying so much about 120 volts is... silly. Electrical tape, covered in duct tape for strength really will work for most applications.



In short, if you have half a brain, and can solder, this should be no issue, and will produce great results.