Testing: How much do fan configs matter? Push vs Pull vs Push/Pull
Testing: How much do fan configs matter? Push vs Pull vs Push/Pull
2016-08-22
what's up guys Jays $0.02 here and I've
done a lot of talking head videos where
I just kind of talk to you and give you
information to try and arm you with
making you better pc builders and buy
the right stuff for your builds because
let's face it everyone has different
needs and one of the videos I did I
think it was last year maybe even the
year before was I talked about fans and
a difference between pull push and push
pull and where you would want to use the
various configs with fans and one of the
biggest pieces of feedback I've gotten
was it would have been nice to see
actual comparisons and you know see it
in actions you guys can actually tell
what the difference is and not just talk
about it
so as we're going to do here today we're
going to we're gonna talk a little bit
about radiators we're talking about
push-pull and we're going to actually do
some comparisons here where we see how
much of a difference there really is
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link down below note I have right here
are two different 120 millimeter fans
both of them have a 120 millimeter
surface area which is you know 12
centimeters by 12 centimeters and they
have a 120 millimeter fan it fits on
them that's how they get their name but
the difference between both of these is
their thickness this is a 30 millimeter
radiator this is a 45 millimeter
radiator which means this has 50% extra
thickness to it which theoretically
leads to it having more overall surface
area in the fin density giving it a
better cooling advantage to its skinnier
counterpart so that's where fans come in
where if you use a thick radiator but
you don't have proper fan config on it
you could actually be doing yourself a
disservice and actually getting worse
temperatures and going with a thinner
radiator if you're not moving air across
those fins efficiently the thicker the
radiator is the more pressure drop
there's going to be on one side versus
the other as the air is going in it's
going to meet resistance with all these
fans because air actually kind of wants
to expand and go sideways and as its
forced straight through these
it's going to lose pressure over
distance so that's why high static
pressure fans actually are recommended
when it comes to radiators and that's
why a push-pull configuration is
recommended on anything 45 millimeter or
thick in my opinion you'll find varying
opinions out there on the Internet
it's kind of funny how that works is
there's lots of facts there's lots of
opinions in a complete disregard for
which ones which but I digress
some would say a 60 millimeter or even
an 80 millimeter would be where you
would need to use push/pull not
necessarily a 45 it's also going to
matter on the fin density how small the
fins are how big the fins are there's
lots of factors there and I did a video
on that as well that you could check out
what you go more in depth on that I'm
not going to bore you here today with
that kind of information we're just
going to kind of keep it high level and
simple for the sake of apples-to-apples
comparison here but as they as the air
is pushed through the fins and forced to
straight now it's going to encounter a
lot of resistance which means that the
pressure going on on one side may not
equal the pressure on the other side and
the goal here with radiators is to try
and get equal air in air out on both
sides of the radiator limiting the
amount of pressure drop which would also
limit the amount of cooling efficiency
that you can have the way a radiator
works is as water is flowing through the
cooling tubes and the heat is being
dissipated through those fins the fans
job is to move that heat away from the
radiator so that more heat can be
absorbed so the more efficient you get
the air across that radiator the better
your radiator is going to work now yes
guys I know there's obviously more to it
than that there's also not only the
thickness of the radiator there is the
overall surface area of the radiator
which means if you were to take 120 and
add another 120 to it making it a 240
even though it's thinner it will have
usually better cooling efficiencies than
going with a radiator that's half as
long but twice as thick so there's
there's a lot of testing we can do here
in lots of material that we can do in
the future but I want to keep this video
a manageable length so today we are
going to focus on an all-in-one cooling
loop that is built into my 1080 hybrid
card because I showed in that video that
I was able to improve the temperatures
quite a bit by getting rid of the fan
that it comes with and going with a high
static pressure fan in a push-pull
configuration so today we're going to
test three things we're going to test
we're going to test pull and then we're
going to do a push-pull with my Vardar
eighteen hundred and fifty rpm fans
which are a high static pressure fan
designed specifically for water cooling
and radiators we're also going to try it
at a bunch of different rpms to see how
much difference there really is but I'm
going to give you some predictions here
now I don't predict that push or pull is
going to be too different at the same
rpm but I do predict that push pull will
allow us to get better cooling at lower
rpms and even better cooling at higher
rpms the nice thing about push-pull is
it doesn't mean you have to run the fans
higher it means you can actually get
away with lower rpms and not have to
deal with nearly as much pressure drop
across radiator alright that's enough
talking head let's go ahead and
turn around get into the test bench and
let's start let's start playing around
in testing this now what you guys are
looking at right now is two identical EK
water block Vardar 2200 rpm fans hooked
up on a PWM splitter on the same PWM
circuit so they are getting identical
voltages here when it comes to fan RPMs
and performance now the one on the left
obviously is hooked up to a high density
thirty millimeter thick 120 millimeter
radiator and the one on the right
clearly isn't an open-air config that
has no resistance either in front or
behind the fan so the reason why I'm
showing you this is to kind of give you
a visual aid as we increase rpms to see
what happens in pull push and push pull
config so that you can visually see
what's happening here then at the end of
all of this what I'm gonna do is
off-camera I'll do all the temperature
testing I'll put together a chart that
way I mean there's really no way to
entertain you while I check the
temperatures I mean I would be really
boring but anyway right now they are
running at 1015 rpm of their max 2200 so
they're less than 50 percent right now
this is at their starting voltage this
is as slow as they can spin so this as
you can see we're getting like hardly
any airflow through the radiator
whatsoever right now and the open air as
you can see is actually moving the paper
now the paper does have a little bend at
the end of it so that it doesn't just
flop around and start waving we want to
get something for the air to catch and
push that way we can actually measure
how much static pressure and airflow is
making it through the fan blade and
resist
itself so as you can see it starting
voltages there's quite a bit of
difference between the two already but
that should be fairly obvious let's go
ahead and kick up the RPM a little bit
let's go to about 1600 rpm and let's see
if there's any difference so as you can
see at 1600 actually fifteen hundred and
ninety-one rpm I digress
there is quite a bit of difference
between the two you can see the fan on
the oak the paper on the open-air fan is
completely extended and that is just I
do I can feel I'm standing quite a ways
from these fans right now and I can
actually feel the airflow from the fan
on the right as you can see the paper
it's no match for the fan it can lift it
no problem so let's go ahead and see
what happens here if we max out the RPMs
and see what happens
alright well there they are at a hundred
percent fan speed as you can see the fan
on the right obviously it's just like no
problems it's even bending the paper
that there's so much air hitting the end
of that little tab that's actually
folding the paper up in the middle but
the radiator fan as you can see seems to
be struggling now it's kind of
interesting here what I'm noticing
through the radiator fan is there seems
to be a bit of a vortex taking place
here and I wish I had smoke or something
that I could show you
I might have to invest in a fog machine
and build a fan testing station actually
show you this because what's happening
here is the air actually seems to be
kind of swirling around so it's being
kind of almost pushed on by on both
sides and let me show you what I mean by
that if I lift up the paper it's
actually being sucked back down now you
physicist or whoever that follow me
might be able to explain what's
happening there the only thing I can
think is it might have something to do
with the venturi effect that's happening
as the air is coming through the
radiator and being forced to straight
now and then suddenly reaching the
atmosphere and allowing to swirl and do
what it wants to do where the fan on the
right is just kind of allowed to do its
own thing there's no influence on the
airflow the radiator is actually
creating almost a bit of a suction
effect where that's just where it goes
if I lift it up it falls back down if I
push it down it pushes back up so I
can't actually explain that one now
people might say the other fan on the
right is actually influencing it it's
not I've already tested this there's if
I was to put something in between them
there would be no difference what
however on the airflow in fact I'll even
point it away so as you can see there's
no difference whatsoever when I do that
but yeah when I lift it up it sucks back
down but when I push it down it pushes
back out so I don't know what's
happening there but there seems to be a
little bit of an influence happening
right there can't quite explain it you
guys tell me alright let's go and move
to push config alright so same test this
is a push config right now they are
running at 1000 rpm as you can see
obviously open air is winning but that
should be no surprise but we want to see
here is now in a push config are we
going to get that weird venturi slash
suction effect I inclined to say no but
let's go and bump up the RPM alright so
here we are at sixteen hundred and
thirty rpm that's 75% on the voltage
there and as you can see obviously the
fan on the right completely unrestricted
no change same test but pushed there we
seem to be pushing the paper out a
little bit now it doesn't really seem to
be having that kind of a weird effect
like you guys saw before so let's go
ahead and bump it up to 100 and see if
it pushes it out now rather than sucking
it back down okay so same thing as
before again guys these fans I promise
are not affecting each other here I can
put my hand right there as you can see
there is absolutely no change whatsoever
to that so the fan on the side is not
influencing the radiator fan whatsoever
but as you can see now we are getting a
pretty decent airflow there through the
radiator it's no longer got that weird
kind of a venturi effect going there so
I think something can be said for the
interference of the airflow in a pool
config versus push I've never actually
tested this so this is news to me
what if anyone's experienced this before
but anyway one last test is go ahead and
go over to push pool and then let's talk
temperatures so there's what a thousand
rpm looks like let's go ahead and bump
it up to 1600 as the fans are ramping up
let's see if you can see it push out
it's at 1,200 1,300 1,400 and 1,600 so
you can see there's definitely a little
bit of improved airflow there obviously
as we're expecting because we've got two
fans working to overcome that pressure
differential and now they're speeding up
to 100% so let's see what happens here
it's kind of funny even with two of
these guys running at 100% they still do
not seem to create nearly as much static
pressure obviously as these fans perform
in an open environment so yeah it's kind
of kind of interesting there if you
think about it I mean all fans are
obviously tested in their most ideal
condition which is completely open so
you need to keep in mind when you shop
for your fans their ratings when it
comes to static pressure because you can
have amazing airflow but it doesn't mean
it can overcome the static pressure yeah
guys I know I'm running airflow fans on
my 560 red on skunk works I'm probably
gonna be changing that on my update so
give me a break all right let's do some
temperature testing
now the results are actually a little
bit different than what I was expecting
I actually expected pull to perform a
little better than push you often here
there can be a couple of degrees
difference between the two which is very
true and as my my charts here have shown
but I was of the belief personally that
pole would be slightly better because it
has no choice but to pull air through
the radiator watch I guess just seemed
to make sense but with because if you
look at the chart here you can see that
push actually performed a little bit
better than pull except at max RPMs
where pull did a little bit better than
push by a couple of degrees in fact
pushed at 49 degrees Celsius max temp at
max RPMs but pulled at 47 but if you
take a look at push it did better in
every other rpm range than max rpm so
what I think might have been happening
here because when I saw that result I
did a little bit of checking a little
bit of testing here was I felt a lot of
air kind of pushing back against the
intake of the fan if that makes sense
when it's and push config what I think
might be happening here is when you have
a high fin density radiator and you have
a high static pressure high rpm fan
there could be a point where you can
actually get a bit of splash or even
back pressure because the air can't make
it through the fins fast enough so it's
got to find a way of least resistance
which is going to be any of the cracks
around the edge of the radiator where
the fan meets and it doesn't you know
actually touch flush or have any sort of
foam protecting air from coming out
besides because I felt some air actually
coming back out the fan where it should
be coming in so there was a little bit
of what appeared to be a little bit of
splash and air coming out the sides so
not all of the air was actually going
through the radiator we're in a pool
config it was able to actually pull
every single ounce of CFM through the
radiator which gave us a little bit
better performance but once you slowed
the RPMs down that was no longer the
case push was then the better performer
at the 1600 rpm and 1000 rpm speeds so
what I think might have been happening
here like I said is a little bit of back
pressure building up now obviously
push-pull was the winner all around 41
degrees Celsius at 2200 rpm overclocked
plus 100% on the voltage 2164
it's on the on the GPU plus 500 on the
RAM I mean I really push the graphics
card as hard as I could to try and build
up heat but this is the first time I've
actually shown you guys tangible results
you can see by just how much anyway if
you guys are looking at doing fan
configs on your radiators if you can fit
it push-pull is going to be the best
result even at lower rpms as you can see
we were getting lower temps at lower
rpms than push or pull independently so
if you have the room for it do push pull
but if you don't then obviously make
sure you have a good static pressure fan
and temperatures will still be just fine
anyway guys thanks for watching here I
hope you enjoyed today's video we'll do
more science stuff remember this these
videos are directly in response to
requests from you guys so make sure you
let me know what you want me to do and
if it makes sense then we'll do it
anyway guys thanks for watching and as
always we'll see you in the next video
you
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