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N-Sanity's Guide To Fans

post #1 of 74
Thread Starter 
--= N-Sanity's Guide To Computer Fan
Selection/Modification/Utilization =--


So, you're thinking of getting some fans for your cool new (or old...)
rig, huh?
Well, i strongly suggest you read what follows below before you do so.

Table of Contents:
3 Types Of Set-ups
Positive pressure system
Negative pressure system
Equal pressure system
Conclusion
Fan Power
Electrical Power
Air power
Noise
Fan Size
Fan Placement
Using Your Fans
Connecting your Fans
Soldiering a 3pin connector on
Soldiering a 4 pin molex on
Controlling your Fans
Software controll
Hardware controll
Overclocking your Fans
Hardware overvoltage
Fan Adapters
Fan protection & service
Random DO's and DONT's
Recommended
Fan controll Software
Fan controll Hardware
Credits

The 3 types of Air Cooling Setups:
The Positive Pressure System:
A positive pressure system basicly means that you have more air going in
then out of your system, therefore inside you have more pressure then
outside.
Your system will stay cleaner, as the pressurized air on the inside will
try to get outside, and since it can also do that by slipping through
cracks and slits in your case, it will. Therefore much of the dust will
get filtered by your case. However, the hot air inside your case will
take a longer time to leave, and will worsen your temperatures by a
LITTLE unnoticable bit.

The Negative Pressure System:
This is obviously the opposite of the positive pressure system, since
inside you have a lower pressure then ont he outside of your case. Dust
will build up more inside your case, since dust will slip IN through all
those tiny cracks and slits in your case, and not get caught by the fan
filters (assuming you have any) however with all the hot air removed
before the cold air is pumped in means simply more cold air will slip in
through other ways, and this setup will have your temps a little lower.

The Equal Pressure System:
In the equal pressure system, the inside of your case is equally
pressurized to the outside of your case. This means you have the exact
same amount of air blowing in and blowing out.
For all you Zen people, this means BALANCE (ooh shiny...). You know the
plusses of that. Basicly a compromise of the negative and the positive
pressure systems.

Conclusion:

For the average Overclocker, a negative pressure system would be the
better choice.
For a lazy couch potato that doesnt care about his inside that much and
therefore will never clean them, a positive pressure system is the
better choice.
As before said for Zen people, and just the general crowd that might
take a peek inside from time to time, an equal pressure system is better.


Fan Power
There are 2 ways you can measure the power of a fan.
One is the amount of electricity it draws, and the other is the amount
of air it moves.

Electricity consumption or power is designated as the letter P in
physics and is measured in Watts (W). Power = V*A*(delta)t
/ (delta)t
. When simply comparing power, we assume the changes
in time (delta t) is equal and therefore we simplify the (delta t's) out
and get V*A (Voltage(volts) * Current(amperes)). Generally the more
power a fan draws the more powerfull it is in terms of moving air. An
average 80mm 25cfm (CFM explained below) 12v fan, will draw about 0.2 A.
That means it 'eats' (12 * 0.2) 2.4 Watts of power. The current rating
is ALWAYS listed on the back of the fan, on a little sticker. So is the
Voltage.

The Amount of Air moved by a fan is measured in CFM
(Cubic Feet / Minute = f^3/m). This describes how many cubic feet of
regular air in an equal pressure environment the fan can move under
ideal curcumstances at full speed and rated power. Pc fans usually come
in the following stereotypes:
60mm fan : 5-30cfm
80mm fan: 10- 80cfm
92mm fan: 15-120 cfm
120mm fan: 20-200+ cfm
There are of course exceptions, but usually this is what you would
expect from that size of a fan.
If you are wondering what all the numbers mean heres a description:
(all descriptions describe a fan at given cfmage at around 10cm from hand)

5cfm: you can barely feel this much
15cfm: you can feel the slight breeze, but its still
not much. You can look straight into it and not close your eyes
25cfm: you can definitly feel the breeze, and if you
look into the fan, you will have to squint
40cfm: you can feel a strong breeze go though your
fingers, and upon looking into the fan you can barely open your eyes.
60cfm: you can feel a pretty strong wind now pushing on
your hand. The fan will probably fall over on its side if it was
standing on an even platform without any support.
80cfm you can feel quite a strong wind push onto your hand.
100cfm you can feel a very strong wind pushing your
hand back considerably.
200cfm this is basicly a good hair dryer....

About 100cfm in your whole computer is very good airflow!

Noise
Noise is one of the biggest factors considered when getting fans.
You want lots of airflow... but you dont want your computer to sound
like a F-18 Hornet fighter.
To measure noise, there are a whopping 22 different scales devised, but
the most widely used one is the Decibel (Dba) scale. The Decibel Scale
is not a linear scale though. It is very similar to the human ear. We
can tell the difference between an average fan at 3000rpm and 4000rpm,
but we cant tell the difference between a Russian Saturn V rocket and a
regular Concord airplane. This is because our ear's sensitivity
decreases logarythmically with sound getting louder.

This is what the decibel scale looks like. As you can see, its not
linear, but logarithmic instead. Heres a nice little diagram to get you
on even ground
.
So therefore, 20dba is a good very quiet fan. 30 dba is not a quiet fan,
35dba is a loud fan, 40 dba is a very loud fan, and 50 dba is like
putting an electric drill to your ear and turning it on. VERY loud. In
your case, the sound will be dampened a little, but nonetheless, you
don't want a 35db computer beside you. Aim for the 30dba mark.
Of course, fans arent super efficient, so at 30 dba, i'd expect you
would get 60cfm from a 120mm fan. As fans get smaller, obviously their
efficiency in terms of airpower vs loudness will drop. At 60cfm, an 80mm
fan might be around 40dba.

Therefore we have to compromise in terms of cfm vs dba.
Btw, just to let you know, 2 30db fans wont sound like 60db. More like
32 - 33. The scale is logarithmic, remember?

Fan Size

Fans for pcs come in a couple of standards:
40mm, 60mm, 80mm, 92mm, 120mm.

Thicknesses vary.
Of course there are other sized fans, but these are the most commonly
used ones, and are the atx standard sizes. The MOST commonly used for
CASE fans are the 80mm and 120mm.

Fan Placement
They way you place your fans is of paramount importance.
Placing them improperly may screw up your airflow and waste all the time and effort you spent. That is why this guide is here.

First of all we need to remember the fact that WARM air RISES and COLD air FALLS.

So obviously, our intakes should be at the near bottom of the case, and exhaust should be at the top.

You want to organize your your airflow properly, because if you have hot air blowing in on your cpu from the top, while cold air is being pumped in at the other side of the case you will get worse temperatures. Try to direct your flow to make sure it covers the important parts of your computer properly.

Using your Fans

Fans most often come with a 3pin connector which fits it's opposite on
your mother board, and with a standard molex 12v 4pin connector. To
connect your fan, plug it either into the motherboard connector if you
have a small 3 pin connector, or to a molex coming out of your power
supply. BE CAREFULL, if your computer is turned on while you do this,
the fan will obviously start to spin right away. There are fans that can
cut your figners right off. Even though i usually connect them to a live
computer because i am too lazy, i advise AGAINST it. I've had half the
skin on my index finger skinned off by my 130cfm 120mm fan (if you would
like to have it, pm me).

Now sometimes, if you dont buy a fan from a retailer, or you accidently
did this yourself, the fan may not have a connector at all. It may just
have 2 or 3 wires coming out of it. In this case, you can do one of 3
things:
You can soldier a connector on it;
You can cut open a 12v molex and soldier it right to the wire (I advise
against this strongly)
Or you can soldier it directly to the motherboard (i advise against this
even more)

Now the smartest and best choice here would be to soldier a connector to
it.

Soldiering a 3pin connector on:
If you have 3 wires coming out of your fan, that usually means it's
speed can be controlled. In this case you would use a 3 pin motherboard
connector.
Red wire goes in the middle, the black to one side and yellow to another
side.
If you dont know how to soldier, heres a guide:
http://www.kpsec.freeuk.com/solder.htm
Soldiering a 4pin connector on:
If you only have 2 wires, or just want to soldier a 4pin connector on,
the red wire attaches to the yellow wire, and the black wire to the one
beside the yellow.

Controlling your Fans
Everyone likes to have controll. It is a genetical fact. Humans like to be in controll, and always avoid being controlled. Well there are very good reasons for that.
Fans also need to be controlled.
You can do this in a couple of ways.
Usually, the 3pin connectors on your motherboard allow controll over fan speed with special software. You can check the list at the bottom for my recomendations.

Another way to controll your fans is to buy a fan controller. These usually come as a device that fits into either your 5.25" bay or your 3.25" bay.
I will also list some below. Many fan controllers also come with displays that usually also show temperature which is very useful, and some are even programmable. Other nice feautures like card readers and front audio connectors are also nice.

If you're not that advanced, there is also another way out.
You can soldier a potentiometer DIRECTLY into the line. Just cut the red wire, and soldier the potentiometer's first leg to it. To the other end of the wire, soldier the 2 legs that are left together. Now, turn on your fan. Twist the dial on your pot and you'll see the fan's speed vary accordingly. I suggest using 5k pots for 80mm fans up to like 0.4a. Over that, try a 10 k maybe? If you're not comfortable with soldiering, you can also simply twist the wire around the pins, and fasten it with glue maybe. That will also work as long as there is a hard metal to metal connection.

'OverClocking' or Modding your Fans
Yes, fans are 'overclockable' in a way.
You can overvoltage them, which means to add more voltage.
There are a couple ways you can do this. The easiest and quickest would be to take a big fat battery and attach it to the fan's power supply through a resistor or a potentiometer. Potentiometer (pots) are simply resistors the resistance of which can be varied. If you plug a battery directly into the line it may be a little too much voltage. Another way would be to build a small device which could connect another 12v line to your fan through a controll circuit. The advantage of this is that you can get a lot more amperage, and of course your not wasting batteries Plus it'd look cool if done correctly.

You can always get more out of your cooler or case by using a fan adapter to use a bigger fan then what would fit your application. There are many 60mm>80mm>120mm adapters available. This also helps with Dead Spots on your fans. These are the spots on a heatsink where your's fan's middle would be. Since the middle is solid and doesnt blow air, no air goes through there. To insure that all parts of a heatsink are effectively covered with airflow, people use fan adapters.

Protecting your Fans
Fans need protection too.
If a fan's blade is scratched, or the rotor is set off balance or its not oiled, the performance will decrease and the noise will increase. Eventually it may just die. To protect your fans, and your fingers, i'd suggest buyng a fan grill.
Most grills come in fancy designs so this will make your fans stand out too!
Very restrictive grills may decrease your performance a little, but in my opinion all your fingers and nails in place is better then 20 extra mhz.
Some people also buy fan filters. These do restrict airflow quite a bit, but on the bright side, you'll probably never need to open/clean your case. Only the filters. However, if you happen to have a negative pressure system, this will be almost useless. Dust will be sucked in through other means.
Also, you should lubricate your fans at least once every 5 years to get the most out of them.
To decrease noise and vibration, you may want to invest in silicon vibration pads.
And last but not least, dont throw coins and crap into live fans to see how far they bounce. First off all that coin on a 1amp 120mm fan can make a hole in ur skull, or ur screen or even wall for that matter, and second of all this unbalances the rotor and scratches the blades.




Random DO's and DONT's
Putting to fans smack-dab together will only decrease theyr performance.

Over volting your fans may kill them or sometimes going a little too far will actualy DEcrease performance.

Connecting too many fans to one molex could cause the system to not function.

Dont put your fingers into live fans.....duuh.

Dont throw anything into ur fans. Theyr blades could become chipped, which will increase noise and turbulance incredibly.

You can decrease the sound level of fans by buyng silicon pads for them. These will dissipate most of the vibration, where a lot of the noise is coming from.

You can oil your fans by taking off the sticker at the back and dropping a tiny drop of lubericant on the little bearing.




Recommended Fan controll software:
Everest : http://www.lavalys.com/products/down...lid=35&lang=en

MoboMonitor5 : http://mbm.livewiredev.com/

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

Recommended Fan controllers:
http://www.newegg.com/Product/Produc...82E16811999137
http://www.newegg.com/Product/Produc...82E16813999504
http://www.newegg.com/Product/Produc...82E16813999217
http://www.newegg.com/Product/Produc...82E16811999140

Images borrowed from:
Heatsinkguide.com
Coolibri.com
fhwa.dot.org
workcover.com
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post #2 of 74
Thread Starter 
I call for a sticky. Who's with me?
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post #3 of 74
after quicky skimming through this guide, this is very worthy of a sticky and in my opinion should be one of the top 20 faqs.
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post #4 of 74
Quote:
Originally Posted by lightsource
after quicky skimming through this guide, this is very worthy of a sticky and in my opinion should be one of the top 20 faqs.
I agree
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post #5 of 74
Agreed. looks great
But why's Speedfan not in it as fanmonitoring software?
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post #6 of 74
Thread Starter 
Quote:
Originally Posted by hyde
Agreed. looks great
But why's Speedfan not in it as fanmonitoring software?
Noted. Soon to be added when i get home. Would you vote for this to be a sticky?
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post #7 of 74
Quote:
Originally Posted by n-sanity
Noted. Soon to be added when i get home. Would you vote for this to be a sticky?
I would it looks really good
post #8 of 74
Stuck for now but n-sanity I removed your disclaimer because they go against the TOS.

Nice work when the FAQ system is back up, you should post it there as well.

Edit: if you do not agree with your disclaimer being removed let me know and I can delete the thread.
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post #9 of 74
Thread Starter 
Naw, its alright. This is the spinoff cut version of the REAL guide i did for someones site exclusively for a pricey sum
Anyway, WOW n-sanity made a sticky! Man shoulda posted that guide here and this there... Not that much more in the other one anyway tho...
Anyway ill keep editing it and it will evolve. I got new thing to put in right now Ty for all your support, and yes im sorry i forgot about speedfan. Will be put it now. Heck this will prolly come out better then the other one :|...

Ok, edit: I added another section See if you can find it in there.
Also added speedfan. Also got some spellings straight.
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post #10 of 74
by just skimming threw it seems usful information
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