Fans Case\Front & Rear

[Russ]

Hi

I am trying to figure out how best to configure the fans in my pc.
I have 2 fans in and at the moment they are not connected to any power
management apart from the force 9 gale blowing up my trouser legs there is a
slight problem with noise. My MB is ASUS P4P800 which has Q fan on the board
there are pins for PSU\CPU and case. Two Fans 1 connecter. I have all so got
one of those voltage reducer things that maplin\Tandy sell. I intend to put
this on the fan that is NOT connected to the motherboard.

I cant decide which is going to plug in where. At the rear I have 120mm fan
which is my exhaust and at the front I have a 90mm acting as the intake.
Would it be better to have the rear controlled by q-fan so as it gets hotter
it sucks more hot air out or should it be the front fan that is connected to
the MB so to suck more cool air in as the temp rises while obviously the
other fan just remains at the same speed.
How best do you folks think i should do this and what about positive a
negative pressure should I concern myself about that?

Secondly the psu fan isn't controlled by the mb as there are only the speed
sensor (yellow wire) and the Negative (black wire) connected the red being
the positive is non existent. Its interesting to know its speed but will it
affect the q fan software and hinder it in any way.

I`ve read page after page on the subject of cooling and the possibilities
and taken that much info in I am unsure which would be the best way best
cooling at minimal db with the fans I have..


Any suggestions People apart from slinging it in the tub,


TIA

 

[Paul]

Hi

I am trying to figure out how best to configure the fans in my pc.
I have 2 fans in and at the moment they are not connected to any power
management apart from the force 9 gale blowing up my trouser legs there is a
slight problem with noise. My MB is ASUS P4P800 which has Q fan on the board
there are pins for PSU\CPU and case. Two Fans 1 connecter. I have all so got
one of those voltage reducer things that maplin\Tandy sell. I intend to put
this on the fan that is NOT connected to the motherboard.

I cant decide which is going to plug in where. At the rear I have 120mm fan
which is my exhaust and at the front I have a 90mm acting as the intake.
Would it be better to have the rear controlled by q-fan so as it gets hotter
it sucks more hot air out or should it be the front fan that is connected to
the MB so to suck more cool air in as the temp rises while obviously the
other fan just remains at the same speed.
How best do you folks think i should do this and what about positive a
negative pressure should I concern myself about that?

Secondly the psu fan isn't controlled by the mb as there are only the speed
sensor (yellow wire) and the Negative (black wire) connected the red being
the positive is non existent. Its interesting to know its speed but will it
affect the q fan software and hinder it in any way.

I`ve read page after page on the subject of cooling and the possibilities
and taken that much info in I am unsure which would be the best way best
cooling at minimal db with the fans I have..


Any suggestions People apart from slinging it in the tub,


TIA

Unplug the fan at the front.

In a push-pull fan configuration, you aren't moving that much more
air - push-pull helps if there is a lot of resistance to air flow
in the case, or can help if you are looking to swirl the air around
inside the case (that has some value, for devices in corners of
the case etc).

There are some cheap drive bay devices you can buy, which give you
a rheostat per fan, to adjust the speed, but the simplest thing is
to just unplug one fan and check to see whether the case temp stays
reasonable. If the "motherboard" temp is 35C or less when the
room air temp is somewhere around 22-25C, that might be a
compromise between cooling and noise.

You could also find some Panasonic Panaflo fans, as they use
a sealed sleeve bearing, instead of ball bearings. This makes
them about 3dB quieter. The fans come in three different
ratings, so it is best to pick the one that provides the
amount of cooling you want, without needing a rheostat to
adjust it.

The only part which is really that sensitive to heat in a case,
is the disk drive. The operating specs for disk drives have a
curve, which includes relative humidity and temperature. For
some of them, 36C and 60+ percent relative humidity is a data
point on the curve. If the room air is less humid, the drive can
take more heat. I lost one disk drive one summer, when my air
conditioning was off for a month, and the humidity climbed to 60%,
as I was blowing outside air through the house, in an attempt to
keep it cool. (I like to think running the computer during
that time, contributed to the failure.)

From an IBM 73LZX disk drive manual - operating limits at
a point above the center of the housing. I don't understand
the purpose of the curve fully, but maybe it has something to
do with moisture condensing on the disk surface. All disk
drives have a breather hole, so humid air from the outside
can get in (through a micron sized filter).

(Select OEM Spec V3.2 - see page 33)
http://ssddom01.hgst.com/tech/techlib.nsf/products/Ultrastar_73LZX

Relative Allowed
Humidity Temp
<14% 55C (very dry winter conditions - good for drives)
60% 36C (carpeting starts to mildew - no AC in summer)
90% 31C (unbearable for humans, and for your drive)

Non-drive components in the computer are more rugged than that.

Paul

 

[Chris]

If your hard drives are behind the front fan, it will help keep them cool.
But if the front of the case doesn't breathe well, it won't pull in any
outside air, thus heating the rest of the case. Best way is to try it
different ways. Measure temps and listen to noise and poick the best
compromise.

Chris

 

[Darkfalz]

I am trying to figure out how best to configure the fans in my pc.

I have 2 fans in and at the moment they are not connected to any power
management apart from the force 9 gale blowing up my trouser legs there is a
slight problem with noise. My MB is ASUS P4P800 which has Q fan on the board
there are pins for PSU\CPU and case. Two Fans 1 connecter. I have all so got
one of those voltage reducer things that maplin\Tandy sell. I intend to put
this on the fan that is NOT connected to the motherboard.

Q-Fan is only for your CPU.

I cant decide which is going to plug in where. At the rear I have 120mm fan
which is my exhaust and at the front I have a 90mm acting as the intake.

Intake = chassis fan.
Rear fans you could connect to your the PSU one.

That's how I have it.

Would it be better to have the rear controlled by q-fan so as it gets hotter
it sucks more hot air out or should it be the front fan that is connected to
the MB so to suck more cool air in as the temp rises while obviously the
other fan just remains at the same speed.

No, I'm not sure those kinds of fans are meant to be thermally controlled
anyway.

How best do you folks think i should do this and what about positive a
negative pressure should I concern myself about that?

Secondly the psu fan isn't controlled by the mb as there are only the speed
sensor (yellow wire) and the Negative (black wire) connected the red being
the positive is non existent. Its interesting to know its speed but will it
affect the q fan software and hinder it in any way.

Q-Fan is only for your PSU. If you got a PSU fan connector, you may as well
use it, but I use the PSU fan socket to power my rear fans (two 60 mm ones).

 

[billh]

Hi

I am trying to figure out how best to configure the fans in my pc.
I have 2 fans in and at the moment they are not connected to any power
management apart from the force 9 gale blowing up my trouser legs there is a
slight problem with noise. My MB is ASUS P4P800 which has Q fan on the board
there are pins for PSU\CPU and case. Two Fans 1 connecter. I have all so got
one of those voltage reducer things that maplin\Tandy sell. I intend to put
this on the fan that is NOT connected to the motherboard.

I cant decide which is going to plug in where. At the rear I have 120mm fan
which is my exhaust and at the front I have a 90mm acting as the intake.
Would it be better to have the rear controlled by q-fan so as it gets hotter
it sucks more hot air out or should it be the front fan that is connected to
the MB so to suck more cool air in as the temp rises while obviously the
other fan just remains at the same speed.
How best do you folks think i should do this and what about positive a
negative pressure should I concern myself about that?

Secondly the psu fan isn't controlled by the mb as there are only the speed
sensor (yellow wire) and the Negative (black wire) connected the red being
the positive is non existent. Its interesting to know its speed but will it
affect the q fan software and hinder it in any way.

I`ve read page after page on the subject of cooling and the possibilities
and taken that much info in I am unsure which would be the best way best
cooling at minimal db with the fans I have..


Any suggestions People apart from slinging it in the tub,


TIA

A word of caution, if you are attaching fans to the motherboard fan
connectors make sure the fans do not draw more than the rated current for
the MB fan connections. You will damage the MB if you do.

Billh

 

[Ghostrider]

Darkfalz wrote:

Q-Fan is only for your PSU. If you got a PSU fan connector, you may as well
use it, but I use the PSU fan socket to power my rear fans (two 60 mm ones).

It might make sense to use Q-Fan on the CPU, provided that
its fan drive does not have its own thermostatic control.

 

[Darkfalz]

Darkfalz wrote:

ones).

It might make sense to use Q-Fan on the CPU, provided that
its fan drive does not have its own thermostatic control.

Wrong. Q-Fan works great with thermally controlled fans.

 

[Paul]

Wrong. Q-Fan works great with thermally controlled fans.

What are the necessary conditions for controlled fans ?

1) If the computer has overtemperature protection, then you are
covered against other failure modes. Asus AMD motherboards now
have COP, and P4 motherboards have hardware throttling in the
processor, plus the 135 degree C Thermtrip# signal to kill the
system.

2) If you combine a rheostat with a fan, either Intel retail fan
or generic uncontrolled fan, then if the rheostat is set low
enough, the fan might not spin. The rheostat is at fault here,
because it is a passive device that doesn't realize the fan
is not spinning. This is an open loop control method.
If you have an older motherboard without protection as in (1),
then be very careful how you use separate voltage reduction
devices.

3) If you use a control method which is "closed loop" and the
method has sufficient voltage to work (i.e. no misadjusted
rheostats in the power path), then there won't be a problem.

QFan is an Asus feature which is based on some conbination of
features in hardware and software. For example, a Winbond
83697HF supports three modes, manual PWM voltage adjust
(i.e. the software adjusts it), "Thermal cruise", and "Fan
speed cruise". Thermal cruise presumably regulates the
temperature of the CPU by upping the fan speed whenever a
threshold is passed, using nothing but hardware.

If QFan is combined with the Intel solution, the closed loop
nature of QFan should still give reasonable control, but the
behavior might be a little strange. At high ambient, the Intel
end will be cranked, but QFan will turn it down if the processor
is idle (that is the good combo of conditions). At low ambient,
the Intel end will be turned down, and QFan will put out nearly
+12V, to try to cool the processor at 100% load. In this case,
the Intel solution is in control, and for a few minutes, the
die temp can shoot up. This means the solution still works,
but it won't regulate the die temperature as closely as using
QFan with a generic uncontrolled CPU fan.

4) If you put two open loop methods in a row, then again, the
fan could stop, because the designer of the individual methods
would have assumed that +12V was being applied to the solution.
If the first method drops the supply voltage to the second
solution to just +7V, then the fan could stop. I am not aware
of any solutions that can be cascaded like this (just included
it for completeness). (If there is an earlier implementation
of QFan that is open loop, and it doesn't actually observe
the die temperature, then that might be a concern. The QFan
design is not the same on every motherboard, just the name.)

The Intel method is attempting to maintain a constant die
temperature, but by an open loop method. The Intel design observes
the ambient temperature, and cranks the fan speed as the local
ambient temperature rises. The increased fan speed improves cooling
effect, and reduces the delta_T between CPU and local ambient.
This gives an approximately constant die temperature, but under
some assumption of the processor throwing off a fixed amount of
heat (which of course isn't correct at all). The end result is
that the Intel solution by itself, can let the die temperature
shoot up and down (as a CPU die heats up in a second or two under
load or removal of load).

For best die temperature regulation, the ability to monitor the
CPU more directly, is what makes QFan better than the Intel method.
Combining QFan with a generic uncontrolled fan means QFan can
work properly under all conditions. Mixing QFan with the Intel
retail fan still works, but die temperature regulation isn't as
precise.

HTH,
Paul

 

[Darkfalz]

For best die temperature regulation, the ability to monitor the

CPU more directly, is what makes QFan better than the Intel method.
Combining QFan with a generic uncontrolled fan means QFan can
work properly under all conditions. Mixing QFan with the Intel
retail fan still works, but die temperature regulation isn't as
precise.

Wrong. QFan doesn't even CARE about the temperature when used with the Intel
HSF fan. It lets the Intel thermal control take care of speed. All it does
in this case is throttle it to a fixed ratio that you have set in BIOS.

So if your minimum RPMs with Q-Fan off is 2700, I'm getting about 2000 RPMs
instead. And when the maximum is about 5500 RPMs, you get about 4000 with
Q-Fan on.

All it does is compensate for the over-agressive nature of the Intel fan.

How it behaves with a non thermally controlled HSF, I'm not sure. But it
certainly recognises the fact the Intel fan has built in thermal functions
and doesn't interfere at all, it just slows it down a bit.

 

[Phil]

A word of caution, if you are attaching fans to the motherboard fan
connectors make sure the fans do not draw more than the rated current for
the MB fan connections. You will damage the MB if you do.

Billh

Or it just won't boot, I had this problem with my CPU fan when I first built
my system, annoying to say the least, I thought something didn't work...

 

[Paul]

Wrong. QFan doesn't even CARE about the temperature when used with the Intel
HSF fan. It lets the Intel thermal control take care of speed. All it does
in this case is throttle it to a fixed ratio that you have set in BIOS.

So if your minimum RPMs with Q-Fan off is 2700, I'm getting about 2000 RPMs
instead. And when the maximum is about 5500 RPMs, you get about 4000 with
Q-Fan on.

All it does is compensate for the over-agressive nature of the Intel fan.

How it behaves with a non thermally controlled HSF, I'm not sure. But it
certainly recognises the fact the Intel fan has built in thermal functions
and doesn't interfere at all, it just slows it down a bit.

I finally found this reference to QFan on an Asus page.

http://www.asus.com/mb/qfan.htm

So, a correction to my post would be to the description
in part (3). If you believe that all Asus boards with QFan
conform to the first figure in the qfan.htm web page, then
QFan is an open loop control method, similar to the Intel
method, but based on a different sensor. QFan delivers a
voltage between (11/16)*12V and (15/16)*12V between 50C
and 60C die temperature, if the BIOS setting is "11/15".
That is, 8.25V to 11.25V. This can be achieved by the QFan
software making manual adjustments to the PWM value in the
chip that controls the fans. (In fact, the hardware in some
fan speed controllers supports 256 values for PWM, so the
Asus method uses a subrange of that.)

The Intel fan on a 3GHz retail processor, varies the fan
speed between 32C and 40C ambient case air temperature.

Combining two open loop methods is only bad if your motherboard
doesn't have any provision to do something if the fan stops.
I don't know how low the voltage to the Intel fan can go,
without the fan stopping under some condition (like low
ambient, and low die temperature). It doesn't matter
in this case, because eventually QFan will crank the speed
up when the die temp hits 50C. (In other words, QFan is
better than a simple rheostat setting the voltage to 8.25V
permanently.)

Reading some posts on various forums, there are suggestions
there, that QFan modifies its behavior if the RPMs drop too
low, but is it hard to say for certain whether this is the
case or not. (I'm not going to waste my time testing this!)

Certainly, using a program like SpeedFan or the like, might
give a user some other options for controlling fans.

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

My personal recommendation to people, is to "keep it simple".
Use solutions that are clearly documented as to how they
work and how the solution behaves under failure conditions.
Yes, very complicated combinations of undocumented control
methods will work - assuming you've tested all the
combinations of high and low ambient temp, high and low die
temp, increased fan friction due to aging and loss of
lubrication and so on.

From the accounts I've been reading, for most P4 people,
Qfan is functioning as a simple rheostat. This is because
their CPU temperature (as measured by Qfan) doesn't get to
50C even under load. So, QFan runs all day at the low setting
(like 8.25V), and the Intel part continues to do its thing
between 32C and 40C ambient, using the lowered value of voltage
supplied to it.

Something I don't understand, is why the Asus implementation
doesn't just modulate the fan speed, to maintain a constant
die temperature. The user would simply set the temp they
want maintained in the BIOS, and the fan speed would be set
to try to achieve that. That is a lot simpler than "11/15".

Live and learn,
Paul

 

[Darkfalz]

The Intel fan on a 3GHz retail processor, varies the fan

speed between 32C and 40C ambient case air temperature.

Yes, this is the problem. Speeding up the fan does NOT lower the ambient
temperature at all. If anything, it makes it rise. The CPU temp itself isn't
really affected.