CPU Cooler designs?

[Vanguard]

Blowing air in (or having no side fan at all) results in the
most pre-heated air flowing over the memory or chipset.
Granted, the air might be slightly cooler.

Slightly cooler? Try 15 C cooler. While my room temperature is 20 C,
the inside temperature is 35 C (no, I haven't gotten to modding my
home PC's case yet). Actually I prefer a quiet PC so I let Speedfan
slow down the fans which lets the inside get hotter unless
temperatures exceed the configured thresholds whereupon the fans speed
up and are more noisy. Cooler internal temperatures would mean cooler
air over the CPU (and GPU). Having to push warmer air over the CPU
means less efficient cooling. If I can get MORE cooler outside air
inside the case then there would be fewer times when Speedfan would
have to speed up the fans.

The key to reducing warm air flowing in circular or
counterproductive directions is to not interfer with the
time-tested and proven chassis airflow pattern from bottom
front to mid-top rear.

Time-tested? Time has shown that the ATX case was NOT designed for
best cooling. It provides absolutely no zoning of airflow. In fact,
it stupidly enforces turbulence because of the twisting required for
the airflow, and turbulence is resistance to airflow. Do you see any
ATX-style cases that have channels built in to keep flat cables out of
the way so they don't block the airflow? Why did they design it so
hard drives could be shoved against each other (so there is no airflow
between them)? Low front intake is okay for drives in the lower cage
but not in the upper drive cage. ATX (without modification) is a poor
design for cooling.

By reducing the bottom front intake rate, by use of a side
intake if not another method, there are lower velocity flow
everywhere except into the 'sink. The exhaust fans will
exhaust at same rate (providing front intake was sufficient)
but a short-loop is created, any air not exhausted into the
air most immedate to the exhaust fan will take a longer path
till exhausted, and slower.

Short loops are exactly what are needed for zoning the airflows to
minimize them from intermingling with each other. Cool the hot stuff
first with direct outside air and expel it immediately.

Side intake is mostly Intel's attempt to ship cheaper
heatsinks with P4, particularly Prescott CPUs.

Wrong. Side intake was to circumvent the ATX spec's poor airflow
design.

The CPU is not the only part that needs cooled

Exactly, so why use the same airflow to cool EVERYTHING? ATX is a
poor design for cooling. Modders knew that for a long time before
case makers starting adding the extra intake/exhaust ports.

This should never be done, it necessarily increases temps of
other parts (unless the case was otherwise unusual in it's
airflow before this fan was flipped over).

Not if you add MORE venting, like adding a top grill and a bottom fan
that pushes air up past the rear of the drive cages and over the
memory sticks. Top venting may simply be using a PSU that has a
grilled front face instead of just a few slits. I get much better
cooling for *everything* by zoning the airflow inside the case. The
CPU gets cool air from the side panel and its heated air passes out
through the backpanel grill (using shrouds). The daughtercards (i.e.,
video) get their own shroud to pull in air from the side panel intake
and out through a rear grill over the cards (get a fat case to add the
grill or buy one with it already there). Add a grill to the bottom
with a fan to blow up and past the backside of the drive cages and
over the memory sticks (add a top grill if you feel the PSU's fan
isn't adequate or it doesn't have a grilled front face). Keep airflow
as linear as possible and minimize turbulence (which includes changes
in direction).

Many cases don't have fans at the front (unless YOU add them) but
instead just passively suck in the air based on the effective rate of
the exhaust fans. If you now add an intake port midstream in the
case, as in the case of a side panel intake fan, the exhaust fans will
be expelling a portion of that air and drawing less in from the front.
You might end up having to add a fan at the front or around the hard
drives to make sure they get sufficiently cooled, too. If the exhaust
fans were expelling 30 CFM (as their maximum) but a new hole is added
at the side that inputs 10 CFM, the exhaust fans are still only going
to expel 30 CFM so 10 CFM less is coming in from the front to cool the
other parts. So, yeah, I see your point but my point is that the ATX
design sucks for cooling. Better cooling was NOT why the ATX spec was
developed.

Almost everyone has seen that taking off the side panel and simply
pointing a table fan into the case lowers temperatures significantly,
so regardless of the ancient ATX case design, you could use side panel
intake fans to better cool your system provided there was an
equivalent rate of exhaust and you don't mind the noise of the extra
fans.

The ATX design doesn't cool that well so sometimes we have to mod the
case to cool *better*. The old ATX design tried to use one major
airflow pattern to cool off everything. Remember that the first ATX
spec had the PSU blowing air into the case and they later decided it
was better to have the PSU fan suck it out. If you read the ATX 2.1
spec (http://www.formfactors.org/developer/specs/atx2_1.pdf), all it
says about airflow is "Chassis venting should be placed strategically
to allow for
proper cooling of other components such as peripherals and add-in
cards." Oooh, wow, what a scientific airflow design ... not! ATX was
designed for *cheap* integration, not for best cooling. The only part
of the spec that addresses specific airflow is in the placement of the
PSU and its fan in close proximity to the CPU to quickly expel the
heat generated by the CPU so doesn't travel to warm up other
components.

Don't get too hung up on claiming the ATX case was designed for a
particular airflow pattern for best cooling. Its spec was NOT
designed for best cooling and its up to you to mod the case (or get
one) based on YOUR cooling needs and component placement. Obviously
you could mod it wrong but it's pretty easy to mod it right and get
far better results than what the ATX spec was designed for which
itself tells you to mod according to your needs. Designers came up
with BETTER cooling designs while sticking within the ATX footprint,
that's why there are cases with extra intake/exhaust ports (but not
all have them strategically placed). If the ATX design really had
considered cooling, it would've zoned the areas to be cooled where,
for the hottest components, outside air is drawn immediately to a hot
component and expelled immediately without it mingling with any other
airflows. If you're hot and sweaty, do you turn on the fan and stand
on the other side of the room? Do you stand behind some other hot and
sweaty person or go get your own fan? Cooling can be VASTLY improved
over the ancient and inadequate ATX-style case. If you can cut
plexiglass (and heat to bend it, if needed) and glue it together to
make your own shrouds (or find a kit that works for you), along with
nibbling to add fans and intake/exhaust grills, you can zone your own
case and get it running almost as cool (for EVERYTHING) as you could
by simply removing the side panel and pointing a table fan at the
innards.

 

[kony]

Hi kony,


Perhaps, but here's something to try.

Run your ordinary ATX fan cooled PC for two hours in the summer
including some time under load. Measure the CPU and MB temps, then
remove the side panel near the CPU, watch the temps FALL like a brick!

If your ambient (room) temp is much higher in summer, it
might be better to make the room hospitible to the user, and
have the system benefit as a side-effect.

If the system is intended to be used in hot environment,
this should be taken into account when designing or
modifying the system cooling.

If you take the side panel off and get lower temp, the real
question is whether the temp was too high before you took it
off. The secondary issue (still quite important) is whether
the OTHER parts are as cool. In general, taking the side
panel off will tend to make the HDDs and other lower-front
quadrant parts run hotter than with it on. Never forget
that the CPU is not the only part that needs to run cool
enough, it is merely the one most people are overly fixated
on- and yet it has a large heatsink.

A balanced system, properly set up, will have a CPU heatsink
of acceptible size. It should never be necessary to remove
the side panel and enough airflow to keep the other
components cool enough, is likewise enough airflow to keep
CPU cool enough. If it is not cool enough and the other
components are, the solution is a heatsink upgrade or to
increase chassis airflow (but the latter increases noise
more than the former, assuming "heatsink upgrade" doesn't
mean merely choosing one with a higher RPM fan on it).

 

[kony]

Slightly cooler? Try 15 C cooler.

Only if the case wasn't designed properly. CPU temp rise is
in direct correlation to chassis ambient temp and the
chassis should not be 15C hotter. If the chassis is that
hot, the other parts were suffering too and putting in the
side duct may make them even hotter.

Remember the system is not only comprised of a CPU, if the
CPU as hot, so are other parts that you may not be
monitoring actively- and if you aren't monitoring them
actively, it can be even more important to have a larger
thermal margin.

While my room temperature is 20 C,
the inside temperature is 35 C (no, I haven't gotten to modding my
home PC's case yet).

What are you using to determine the case temp? If you rely
on the "system" or "case" temp resport via software, I
presume you realize that is often not the actual chassis air
temp but rather, of a different chip that produces it's own
heat.

Actually I prefer a quiet PC so I let Speedfan
slow down the fans which lets the inside get hotter unless
temperatures exceed the configured thresholds whereupon the fans speed
up and are more noisy. Cooler internal temperatures would mean cooler
air over the CPU (and GPU). Having to push warmer air over the CPU
means less efficient cooling. If I can get MORE cooler outside air
inside the case then there would be fewer times when Speedfan would
have to speed up the fans.

There is no need to speed up the fans at 35C, so there is
either more significant information lacking in your
description, or another issue (which is likely chassis
airflow, if the actual chassis air temp is 15C above room
ambient). Even if the latter is true, we can ignore the CPU
temp and not throttle up fans, rather focusing on the other
parts. Remember that the CPU is more heat resistant than
many of them, and has a longer expected lifespan too.

Yes

Time has shown that the ATX case was NOT designed for
best cooling.

"Best" is arbitrary if you only focus on CPU temp,
particularly when you describe above a CPU that is not even
remotely close to overheating!

It provides absolutely no zoning of airflow.

Wrong, it does far better than having a side duct. WIthout
the side duct there is a clear airflow path from bottom
front to mid-top rear. Add the side duct and the bottom
front will necessarily have lower airflow rate.

In fact,
it stupidly enforces turbulence because of the twisting required for
the airflow,

Turbulence ON the parts being cooled is exactly what you
want. Turbulence in the rest of the case is minimal, it is
proven so and WAS TESTED when ATX was spec'd. They didn't
ignore cooling of everything but the CPU though, which seems
to be what you are doing even when CPU is far cooler than it
needs be.

and turbulence is resistance to airflow.

Inside a chassis that is much larger than the intake or
exhaust areas, the effect of turbulence is minimal, beyond
consideration.

Do you see any
ATX-style cases that have channels built in to keep flat cables out of
the way so they don't block the airflow?

It is a marketing feature unless the system integrator has
no idea how to route cables properly. Plenty of system
builders have demonstrated, millions of times, that a case
with ribbon cables and no channels built in will run fine IF
the primary considerations are considered- and they don't
require a side duct, rather as mentioned previously, the
side duct interferes with airflow around cables by reducing
the amount of airflow in this region. IF your side-duct
was blowing out of the case instead of in, it would increase
the airflow around drives, cables, but this then decreases
airflow around (many if not all) CPU VRM circuits, and out
the PSU, and possibly through the CPU heatsink too.

Why did they design it so
hard drives could be shoved against each other (so there is no airflow
between them)?

Your proposition of the side duct does not change this, only
further reducing airflow there.

Further, you only assume they designed to have drives
"shoved up", when in actuality it was case manufacturers
that only tried to put the most drives in the least space
possible that resulted in the "shoved" scenario.

Low front intake is okay for drives in the lower cage
but not in the upper drive cage. ATX (without modification) is a poor
design for cooling.

Drives in the upper cage are also cooled worse if you
introduce a side duct, unless you had the duct opposite the
rack (which is almost never done, it's far lower).

A better question is why you feel they are not cooled well?
Optical drives do not need a lot of airflow, those that are
particularly hot running tend to have a fan in their casing
but once designs that weren't so hot were produced, the fans
were eliminated. If you have a hard drive up there, you are
choosing to not adhere to the normal component placement and
as such, are taking it upon your self to provide a front
intake (perforated if not actively fan cooled) front
faceplate to accomodate this change in drive location.

ATX does accomodate drives fine, if you don't assume some
poorly made case defines what ATX is, rather than the truth-
that ATX is the definition and the poorly designed case made
other design mistakes.

Short loops are exactly what are needed for zoning the airflows to
minimize them from intermingling with each other.

Short loops are robbing the lower front area of the case,
unless you then add a front mounted fan which increases
noise level and then reduces the effect of the side duct.

Intermingling is exactly what your side duct causes, because
you prevent the airflow from going in the proven effective
path from bottom front of case towards the rear, by reducing
the flow rate significantly. This is proven fact and was
taken into account and measured when ATX was spec'd.

Cool the hot stuff
first with direct outside air and expel it immediately.

Wrong, you have to consider the pressure gradients, to have
suction sufficient enough to intake air into the front of
the chassis unless you add another fan which has drawbacks
as mentioned above. Go ahead and add several addt'l fans if
you like, but if you do that you again eliminate the need
for the side duct by more directly addressing the problem
with your case (if it actually has 15C rise in internal air
temp). Actually, if you case has that high a rise, it would
possibly indicate the problem in airflow that I've already
described.

Wrong. Side intake was to circumvent the ATX spec's poor airflow
design.

You have supplied zero evidence of this, thus far only
describing a chassis that is overheating, then that the CPU
is overheating as a result unless you add a side duct. You
have still ignored the REST OF THE OVERHEATING PARTS.

A CPU can run at 60C for years, longer than parts like HDDs,
fans, motherboard can.

Exactly, so why use the same airflow to cool EVERYTHING?

"Same airflow" means a pseudo-linear path, because this
maximizes flow rate per fan over everything.

You are ignoring a primary detail in system cooling, that
your CPU was not described as overheating and you are not
reporting temps and temp changes of any other parts. This
is a HUGE MISTAKE and quite often why hard drives die.

ATX is a
poor design for cooling. Modders knew that for a long time before
case makers starting adding the extra intake/exhaust ports.

Actually, the vast majority of systems sold and running
today are OEM systems, and they do not have all these
changes the modders made. It may be true that if a
so-called modded had a poor generic case, they needed to
make "some" kind of change to it, and they may not make the
best choice from a airflow:noise ratio perspective, OR they
might be overclocking without a suitable heatink, or as
mentioned several times already, they may not be focusing on
any parts temps except the CPU and system (actually another
chip temp).

BTW, I mod plenty of cases, even early ATX that had no aim
of cooling today's higher heat parts, even overclocking
parts quite a bit as a hobby and do not need to do these
things you imply are important- because I actually meaure
temps of ALL parts that heat up and observe the temp
changes. Most modders don't do this, they just throw a lot
of fans at a situation and end up with a loud system...
certainly louder than Dell et al. OEMs produce.

It is possible to add enough very large, low RPM fans to
offset this and still have low noise:airflow ratio, but then
the expense goes up for quality fans or the maintenance of
these cheap fans increases, and fans mounted on exterior
walls of the chassis always let more noise escape, because
there's nothing to really "escape", they're already facing
the external room.

Not if you add MORE venting, like adding a top grill

LOL.

A top grill is almost never a good idea. If the case were
incredibly poorly designed to it was starving for air, or
had a very very poor PSU that was overheating more than
anything else, having the top vent increase airflow might
seem to help, but still robs the lower front quadrant of
airflow, it is a poor choice in resolving the prior choice
of a poor case in general. Such a modder shows they have
made two mistakes, choosing a bad case then choosing a
lesser effective mod and one that may actually reduce
airflow in other parts of the system.

There are plenty of examples of ATX cases that run fine
without these kind of misguided hacks. You are attempting
to suggest ATX is a problem when ATX was not the variable,
rather the other aspects of particularly poor cases were the
variable.

It doesn't really matter if you agree, there are plenty of
examples of ATX cases cooling fine. The most significant
problems with ATX are these two:

1) CPU manufacturer that provides a cheap heatsink that
needs help. The word Prescott comes to mind and the entire
industry has already acknowledged it and praised subsequent
CPUs for not having this known problem.

2) Video cards with very high heat and small heatsinks so
as to not block one or more PCI slots.

In summary, I will repeat what I wrote above as it is key in
your misunderstanding:

You are attempting to suggest ATX is a problem when ATX was
not the variable, rather the other aspects of particularly
poor cases (and system setup) were the variable. When
someone takes on the role of system designer, selects parts
that don't work very well, only then do they have to find a
solution and what you have described is an attempt to
band-aid the problem instead of addressing it directly, then
ignoring the effects on anything but CPU that was not
overheating at all per your description.

I have demonstrated exactly what i have described far too
many times to count, as have the majority of systems running
today made by most OEMs.

 

[Timothy Daniels]

Turbulence ON the parts being cooled is exactly what you
want. Turbulence in the rest of the case is minimal...

You've done a 180º on THAT, Kone-head.

Inside a chassis that is much larger than the intake or
exhaust areas, the effect of turbulence is minimal, beyond
consideration.

You've done a 180º on THAT, Kone-head.


I think I'll call you "One-Eighty Kone-Head".

*TimDaniels*

 

[Timothy Daniels]

Keep in mind that the manufacturer's design of the case
must conform to FCC spurious emission requirements
which preclude opening large holes in the chassis. I
really don't know how the "game machine" manufacturers
get away with their plexiglass sides - unless those sides
have a metal film or the manufacturers' low volume production
exempts them from FCC requirements.

*TimDaniels*

 

[kony]

You've done a 180º on THAT, Kone-head.

Nope, read more carefully.

You've done a 180º on THAT, Kone-head.


I think I'll call you "One-Eighty Kone-Head".

I think I'll call you miserable.
You torment yourself and falsely assume trolling will help.
Obviously not Tim, or it would've done so already.

 

[kony]

Keep in mind that the manufacturer's design of the case
must conform to FCC spurious emission requirements
which preclude opening large holes in the chassis.

No they do not have to conform!

An assembled, whole system must pass such tests but a case
alone does not have to.

I
really don't know how the "game machine" manufacturers
get away with their plexiglass sides - unless those sides
have a metal film or the manufacturers' low volume production
exempts them from FCC requirements.

See above, it doesn't have to meet a spec because it has no
power plug and produces zero emissions AS-SOLD.

 

[q_q_anonymous]

Hi,

As I understand it, most ATX style PC setups have a fan above the CPU
that blows air down onto the CPU to keep it cool, and the hot air
bounces around inside the PC case until it can find an exit (if it's lucky).

As I see it, there are two problems with this,

darn right!!! but no how you think.

The fans have been installed backwards!!!!!!

The (CASE FAN) fan above the CPU is an exhaust fan. It blows the hot
air out of the computer.

There is also an intake fan on the front at the bottom. Usually hidden
"thanks" to the cases with snazzy fronts and some tiny hole somewhere
stopping you seeing how it can get any air in. But if you open the
computer you'll see a space there to fit a fan.

this also makes sense because hot air rises.

I'm sure I once saw a picture in a document called AMD cooling
requiremetns or something, that showed an arrow indicating the
directino of the air. Anyhow, it is like that.

a) unless you have a vent in the side of the PC case, the air being
taken in by the CPU cooler will not be cool, because it's air from
inside the PC case?

Interesting point. I think I saw in a scott mueller video that CPU
heatsinks do **Suck** air downwards and blow it out the bottom. I
almost forgot about that.
Where did you read that?

b) the hot air from the bottom of the heat sink ends up warming up the
Motherboard?

I was looking at the Dell CPU coolers of the GX280, GX620 workstaions
(Intel P4 / Pentium D) and the PE2400, PE 2600, PE2800 servers (Intel
Xeon). The design is completely different. The air is sucked in from the
front of the case, straight over the CPU and out of the back - how cool
is that? Pretty cool, and there's hardly any noise either.

the front of the case is nowhere near the CPU. And generally the fan
is at the bottom front.

The CPU is at the back of the case near the top, just below the PSU.
It's impossible for a front fan to suck air in over the CPU. It's far
away. It just sucks air into the case.
Unless this server is somehow unlike any computer i've ever seen. But
if it uses an ATX MBRD then I find that hard to contemplate. You
should have included a picture - if you could find one.

 

[Timothy Daniels]

No they do not have to conform!

An assembled, whole system must pass such tests but a case
alone does not have to.

So now you're pointing out that an empty case does not
have to conform to FCC requirements. What an insightful
comment! Wot an idiot you are. Even if you have nothing
valuable to add, ya gotta keep spewing.

*TimDaniels*

 

[Timothy Daniels]

Nope, read more carefully.

Riiiiight - as you've said before, "turbulence ON the parts is
what aids their cooling, NOT turbulence hitting the parts".
Please differentiate between the two for us Kone-Head,
you'll say ANYTHING FOREVER to be the last one posting.
Start spewing....

*TimDaniels*

 

[kony]

Riiiiight - as you've said before, "turbulence ON the parts is
what aids their cooling, NOT turbulence hitting the parts".
Please differentiate between the two for us Kone-Head,
you'll say ANYTHING FOREVER to be the last one posting.
Start spewing....

Turbulence before the air gets to the part, decreases
chassis intake and exhaust rates to whatever extent this
turbulence persists.

Turbulence on the part is necessary for best effectiveness
of the sink.

The goal is to keep the air moving at good rate, only slowed
down when meeting it's purpose.

Let's look at another example-

You have a lizard that eats insects. It's using camouflage
to sit still and wait for the insects to come near it. It
wants, even needs if to be able to eat enough, for the
insects to approach at a certain rate, then for those
insects to sit still at least long enough to be captured by
it's tongue.

If the insects each in turn, sat still for a long long time
at each interval prior to moving close enough for the lizard
to eat them, which is a lower average rate of travel, the
total insect:time ratio is lower. So the lizard wants them
coming as fast as possible, but the shorter the time spend
in front of the lizard, the lower the insect:capture ratio
is.

The lizard may survive if there are enough insects that
their average rate of travel doesn't matter, and likewise a
computer if someone stuffs extra fans in it to combat the
excessive turbulence extraneous to hot parts contact.

The optimal solution is not to add those fans, not to
interfere with their flow rate either- it's to retain
maximum flow to the parts by the cooling system, and the
rate of exhausting that hot air out of the system. The
(average) ambient temp of the semi-enclosed system depends
on this intake:exhaust rate, so if the total I/O airflow
rate is reduced, it heats up less for each subsequent time
interval because it is closer to the temp of the part
surface it had just been in contact with.

Naturally I don't expect you to agree at all Tim, you were
still trolling as usual but maybe other people won't be as
confused as you are about these OBSERVABLE phenomena.

Again Tim- the reason why cases have the holes in the front
is to keep the ratio of opening to opening length minimized
for reduction of EMI. It would be a trivial thing to set a
metal stamp to a more complex pattern to increaes turbulence
if that were their goal instead.

 

[kony]

So now you're pointing out that an empty case does not
have to conform to FCC requirements. What an insightful
comment! Wot an idiot you are. Even if you have nothing
valuable to add, ya gotta keep spewing.

So:

1) You didn't know.

2) You assumed you did.

3) Your assumption was in error.

4) You'd tried to pretend you know something only assumed.

5) You attempted to propigate this pseudo-knowledge.

6) You trolled like a brat child when found wrong.

7) You were schooled so well that it then seemed obvious.

8) Even then you troll and whine.

9) Tim is an idiot.

10) We already knew that.

 

[Timothy Daniels]

"kony" spewed:

So:

1) You didn't know.

2) You assumed you did.

3) Your assumption was in error.

4) You'd tried to pretend you know something only assumed.

5) You attempted to propigate this pseudo-knowledge.

6) You trolled like a brat child when found wrong.

7) You were schooled so well that it then seemed obvious.

8) Even then you troll and whine.

9) Tim is an idiot.

10) We already knew that.

Even if Kornball has nothing valuable to add,
he's gotta keep spewing. He absolutely *must*
have the last word.

*TimDaniels*

 

[Timothy Daniels]

"Timothy Daniels"



Turbulence before the air gets to the part, decreases
chassis intake and exhaust rates to whatever extent this
turbulence persists.

Turbulence on the part is necessary for best effectiveness
of the sink.

The goal is to keep the air moving at good rate, only slowed
down when meeting it's purpose.

Let's look at another example-

You have a lizard that eats insects...

Spare the lizard parable. If there is no turbulence when
the air gets to the part - a heatsink in your example -
the calm laminar air flow past the part will have to build
up turbulence as it passes so as to scrub down through
the boundary layer to contact the part itself. You think
this "self-turbulence" as you've called it is more effective
than turbulence already generated upstream from the
part. Please explain why cooling turbulence generated
at the part is more effective than turbulence generated
upstream, given that you've said:
"Turbulence ON the parts being cooled is exactly what you
want. Turbulence in the rest of the case is minimal..."

*TimDaniels*

 

[Tom Goodman]

I did some calculations to find out what the swept areas of my front
bottom and rear top case-fan blades were. Not surprisingly both figures
were greatly below the quoted fan diameters.

I then measured the diameter of the little holes which were punched in
the computer case in the fan-blade swept area, multiplied by the number
of holes to arrive at the actual area through which the fans could
exhaust air.

Horrified by these figures (work your own out and report to us) I then
hacked out all the metal corresponding to the fans swept area plus the
central cylinder (the motor) and then found that cooling was, not
surprisingly greatly improved. Because of the reduction in airflow
impedence the fans worked more efficiently and could either be left at
their original voltage for better cooling or run slower and more quietly
for the same cooling (actually slightly better because the fans
themselves consumed less power working at reduced airflow impedence.

For one fan report

Fan make and nominal diameter, swept area of blades, case-fan efficiency
I define as (total holes area in swept area/swept area) x 100, voltage
setting if not stock, fan RPM and CPU+ other temp values before metal
removal.

Then quote values for temp, RPM after metal removal with same voltage or
stock.

Use metric for uniformity please, ie centigrade and mm.

I guarantee that the results will surprise you all.

Finally, can anyone suggest a better tool than a drill and hacksaw for
the metal removal please ? (better to remove all components and then
vacuum of course or better still before building. I used polythene sheet
to isolate the interior)

I hear there is a nibbling tool, but what is it and can it be bought in
London ?

 

[kony]

Spare the lizard parable. If there is no turbulence when
the air gets to the part - a heatsink in your example -
the calm laminar air flow past the part will have to build
up turbulence as it passes so as to scrub down through
the boundary layer to contact the part itself. You think
this "self-turbulence" as you've called it is more effective
than turbulence already generated upstream from the
part.

No, I think turbulence on the part surface does not mitigate
the need to maintain a good rate of fresh, cooler air to the
part and also remove the pre-heated air.

Your ideas about creating tubulence have involved creating
it at the entry to the system, where it has a _DIRECT_
impact on flow rate, obviously decreasing it.

The goal is to increase turbulence without interfering with
the intake and exhaust rate. If you can manage to do this
with some kind of special *device* just before the hot part,
fine, except you still ignore than this creation of
turbulence will also, still reduce the rate of aiflow to
that part.

Further, you continually ignore than the turbulence created
at entry to the system is at a reduced level by the time it
has reached the hot parts- they are not immediately adjacent
to the turbulence-producing obstructions.

Essentially, yes to a limited degree the "self-turbulence"
is more effective, because it doesn't reduce airflow prior
to reaching the part being cooled. Always remember that
maximizing contact between air and the 'sink is NOT the
goal- after a certain point this air has heated up some and
it is more effective to get it out of the case, expediently
(which also includes, least intake turbulence to improve
axial fan effectiveness on the exhaust), than not.

Consider the best heatsinks. What would it cost them to
have a piece of plastic just prior to the 'sink metal with
magic turbulence-inducing holes? Almost nothing, plastic is
cheap and easy to mold as desired. Who does this?

Your theorys are wrong and shown so with every heatsink in
existence. Go ahead and fabricate such a
turbulence-inducing structure in front of your CPU heatsink
then tell us if it helps! This is an easy thing to do and
easily measured resultant CPU temp. (Hint- it will only
decrease the performance, increase the temp if enough of a
change to measure at all).

 

[Rod Speed]

I did some calculations to find out what the swept areas of my front
bottom and rear top case-fan blades were. Not surprisingly both
figures were greatly below the quoted fan diameters.

I then measured the diameter of the little holes which were punched in
the computer case in the fan-blade swept area, multiplied by the
number of holes to arrive at the actual area through which the fans
could exhaust air.

Horrified by these figures (work your own out and report to us) I then
hacked out all the metal corresponding to the fans swept area plus the
central cylinder (the motor) and then found that cooling was, not
surprisingly greatly improved. Because of the reduction in airflow
impedence the fans worked more efficiently and could either be left at
their original voltage for better cooling or run slower and more
quietly for the same cooling (actually slightly better because the
fans themselves consumed less power working at reduced airflow
impedence.

For one fan report

Fan make and nominal diameter, swept area of blades, case-fan
efficiency I define as (total holes area in swept area/swept area) x
100, voltage setting if not stock, fan RPM and CPU+ other temp values
before metal removal.

Then quote values for temp, RPM after metal removal with same voltage
or stock.

Use metric for uniformity please, ie centigrade and mm.

I guarantee that the results will surprise you all.

Finally, can anyone suggest a better tool than
a drill and hacksaw for the metal removal please ?

A nibbler.

(better to remove all components and then
vacuum of course or better still before building.
I used polythene sheet to isolate the interior)

A nibbler would be better there too, bigger bits of metal.

I hear there is a nibbling tool,
Yep.

but what is it
http://www.google.com.au/search?hl=en&q=nibbler

and can it be bought in London ?

Yep, even the wilds of that soggy little island.

http://www.google.com.au/search?hl=en&q=nibbler&meta=cr=countryUK

 

[kony]

I did some calculations to find out what the swept areas of my front
bottom and rear top case-fan blades were. Not surprisingly both figures
were greatly below the quoted fan diameters.

I then measured the diameter of the little holes which were punched in
the computer case in the fan-blade swept area, multiplied by the number
of holes to arrive at the actual area through which the fans could
exhaust air.

It's not quite that simple, particularly with stamped-out
metal holes because they increase turbulence, reduce flow
rate more than you'd otherwise have per diameter of opening.

Horrified by these figures (work your own out and report to us) I then
hacked out all the metal corresponding to the fans swept area plus the
central cylinder (the motor) and then found that cooling was, not
surprisingly greatly improved. Because of the reduction in airflow
impedence the fans worked more efficiently and could either be left at
their original voltage for better cooling or run slower and more quietly
for the same cooling (actually slightly better because the fans
themselves consumed less power working at reduced airflow impedence.

Yes, what you have done is very desirable for reducing heat
in poorly designed cases or improving flow:noise ratio in
any case, unless you're an OEM with EM emissions to combat.

Removing those stamped holes also decreases dust buildup
that further blows exhaust and intake, and allows lower fan
RPM which increases the fan lifespan.

For one fan report

Fan make and nominal diameter, swept area of blades, case-fan efficiency
I define as (total holes area in swept area/swept area) x 100, voltage
setting if not stock, fan RPM and CPU+ other temp values before metal
removal.

Then quote values for temp, RPM after metal removal with same voltage or
stock.

Use metric for uniformity please, ie centigrade and mm.

I guarantee that the results will surprise you all.

Finally, can anyone suggest a better tool than a drill and hacksaw for
the metal removal please ? (better to remove all components and then
vacuum of course or better still before building. I used polythene sheet
to isolate the interior)

I hear there is a nibbling tool, but what is it and can it be bought in
London ?

I have no idea if it can be bought in London, I presume
"somebody" carries them- try a metal supply shop, for trades
like HVAC (you might call a larger local HVAC company and
ask them- many may have ongoing relationships with such
suppliers). There's probably someplace on the internet as
well, but never having looking for one in London...

Hand nibblers are good for 0.6mm, maybe 0.8mm sheeting.
They aren't so good at making nearly perfect rounded holes,
they snip off a few millimeters at a time in a straight
line. You can try to rotate the tool while cutting with
limited success, but it's not going to be a finished look if
the metal isn't pretty thin- if you've worked with hand
tools a lot and have very strong hands and forearms, you can
muscle it into curving more as it cuts but it's not the
ideal tool for the job on anything but straight cuts- though
it doesn't leave tiny metal shavings everywhere, does have
that going for it.

There are electric nibblers or shears too (the former better
for tight areas, the latter better for steel over 1mm
thick), in a wide variety of prices depending on the quality
of the tool. Often over $200 USD. Seldom do I hear of
anyone using one for casework, but if you did a lot of it
and cut out rectangular holes it might be useful.

If the case is small, and 0.8mm or otherwise 1.0mm or more
and the case is fairly well designed (sufficient folds and
bracing such that it doesn't vibrate as much) I find an
(electric) sabre saw better at the task, and of course
drilling the starter holes where necessary. Using a very
fine toothed blade is important, otherwise you may end up
with ripples in the metal.

Some people prefer to use a hole saw, but since the fan
housings flare out I prefer to cut a near square hole with
sloping corners around the mounting holes. It can help to
rip around a cheap fan in the sizes you use and use it's
frame as a template for marking out the case. Masking tape
along the sides of the cuts help to preserve the case finish
with the sabre saw or other tools which glide along the
surface while cutting.

Metal particle removal must be thorough, some cases can be
washed out but others it would take so much time to remove
pieces that a good old paint brush and strong magnet get
enough off and I've never had a problem with that method
either. Most often I don't cut out the newer cases though,
I prefer the older ones as they more often had thicker metal
and without holes everywhere you can better control where
your intake and exhaust is, and have a better looking result
if your fan hole is in a solid paneled area rather than in
the middle of, interrupting a bunch of stamped holes. For
example, some of the old HP cases stamped out fairly odd
shaped patterns on the rear and used a 92mm fan, but the
holes extend further than the fan frame (were only blocked
by HP's inclusion of a plastic duct/snorkel assembly that
extended down towards the CPU 'sink).

 

[Gerry_uk]

Hi q_q_anonymous,

Scroll down...

darn right!!! but no how you think.

The fans have been installed backwards!!!!!!

The (CASE FAN) fan above the CPU is an exhaust fan. It blows the hot
air out of the computer.

There is also an intake fan on the front at the bottom.

No, I'm not talking about the intake fan or outtake fan, I'm talking
about the CPU fan, the one that is part of the CPU cooler. As I
understand it, this fan blows DOWNWARDS onto the CPU.

Interesting point. I think I saw in a scott mueller video that CPU
heatsinks do **Suck** air downwards and blow it out the bottom. I
almost forgot about that.
Where did you read that?

I thought it was common knowledge, but wanted clarification.

The CPU is at the back of the case near the top, just below the PSU.
It's impossible for a front fan to suck air in over the CPU. It's far
away. It just sucks air into the case.
Unless this server is somehow unlike any computer i've ever seen. But
if it uses an ATX MBRD

The Dell machines don't use ATX. You are right that not everyone on this
group is familiar with the Dell business line of machines so it was
probably a bad example. You can however, see pictures of the models I
listed on the Dell site.

The way they have done it is to have a desktop case, with the CPU right
at the front of the mainboard. The air is taken in the front of the
case, straight over the CPU and ducted out the back. It's very cool and
very quiet even with Pentium D's and Pentium 4s at high Ghz. Note that
I'm not talking about Dell home PCs here, only the business PCs.

The Dell servers are similar in their use of ducting, but the fans are huge.

 

[Andy]

Finally, can anyone suggest a better tool than a drill and hacksaw for
the metal removal please ? (better to remove all components and then
vacuum of course or better still before building. I used polythene sheet
to isolate the interior)

I hear there is a nibbling tool, but what is it and can it be bought in
London ?

I use aviation tin snips
<http://www.mrtool.com/browse.cfm/4,756.html>.