fan mods, fan controller, and wirings

[WhiteFireDragon]

when you connect multiple fans together, they hook up in series meaning one behind the other in an electrical loop. i want to stray away from this and had a few questions.

1) can they be connected by parallel? for example, can i use a Y cable to merge two fans to one line or solder the wires of 3 fans together and have it go to one power source? meaning for 3 fans, solder the 3 red wires together and the 3 black wires together. would this result in each fan having lower power and rpm since the line has to split it 3 ways? here's a picture of what could be use for a parallel connect:



2) if i use a fan controller, is it possible to have each control channel control more than one fan? (either by series or parallel). if so, which configuration would be best? here is a drawing:

parallel


series


would each knob control all 3 fans the same as if only one fan were connected or would each fan have reduced rmps?

3) can i solder all the red wires together and all the black wires together instead of using the connectors? i want to do this because connectors take up space and sometimes the wires are too long.

4) is there any negative affect of using the 3-pin to molex adaptor? this one:



5) i noticed that on a fan with a molex connector, some fans dont use all 4 pins (only the red positive and black negative) what are the other two unused pins for? i'm guessing one is ground and the other?

i ask all these questions because i have a bunch of fans in my case i need to manage the cables better by either shortening them or removing the stock molex connectors.

[Big_Daddy]

when you connect multiple fans together, they hook up in series meaning one behind the other in an electrical loop. i want to stray away from this and had a few questions.

1) can they be connected by parallel? for example, can i use a Y cable to merge two fans to one line or solder the wires of 3 fans together and have it go to one power source? meaning for 3 fans, solder the 3 red wires together and the 3 black wires together. would this result in each fan having lower power and rpm since the line has to split it 3 ways? here's a picture of what could be use for a parallel connect:


2) if i use a fan controller, is it possible to have each control channel control more than one fan? (either by series or parallel). if so, which configuration would be best? here is a drawing:


would each knob control all 3 fans the same as if only one fan were connected or would each fan have reduced rmps?

3) can i solder all the red wires together and all the black wires together instead of using the connectors? i want to do this because connectors take up space and sometimes the wires are too long.

4) is there any negative affect of using the 3-pin to molex adaptor? this one:


5) i noticed that on a fan with a molex connector, some fans dont use all 4 pins (only the red positive and black negative) what are the other two unused pins for? i'm guessing one is ground and the other?

i ask all these questions because i have a bunch of fans in my case i need to manage the cables better by either shortening them or removing the stock molex connectors.

1. Yes, fans can be connected in parallel, You can use the y cable, or solder the red's and blacks together, If you want to monitor RPM's only use 1 yellow wire, don't connect them. It will freak out your controller. Also, it won't lower your rpms, it will increase current. Make sure your fan controller can handle the additional draw from 2 or more fans. (Sunbeam Rheobus Extreme can handle 30 watts of power, on each channel, that's alot of fans)

2. Yes, see above. (always use parallel)

3. yes, Here's a pic of me splicing my wires together for my rad.


4. Nope, But that's a funny one, Doesn't look like it actually plugs into a fan (has female, same as fan end) the 3 pin connectors sometimes don't carry enough current to power the big boy fans.

5. 4 pin molex connectors carry +12 (yellow) Ground (black) Ground (black) +5 (red) Fans will take the +12 and ground off of the 4 pin molex. the 3rd cable on a 3 pin fan connector is for rpm sensing. (yellow, blue, white, whatever it depends on the manufacture of the fan)

[WhiteFireDragon]

if i have them in series instead of parallel and connect them to a one of the fan controller channel, how would this be different or what would happen?

[Big_Daddy]

Well, then they would all run slower, if they even powered on.

[MpG]

When you wire fans in series, the total input voltage is split across each fan. Assuming the fans are identical, the voltage is split evenly. So if you have two fans wired in series, and you're running them off a 12V source, each fan is technically running on 6V. For three identical fans, 4V/fan (which many fans won't even start at, so be careful).

In parallel, each fan sees the full voltage coming from the source, and therefore gets the full corresponding current, no matter how many there are, or what kind of power they're each rated for. The only issue is whether or not the source of power is capable of supplying the full amount of current for all the fans together.

For a fan controller, you almost always want to use a parallel hook-up. Series is rare, since the effective undervolting makes the controller kind of redundant. Make sure your wire splicing is secure (good example from BD above, although I hope you used a little heat-shrink/elec tape afterwards).

[Big_Daddy]

Yah, sure, youbetcha...

[Cpl Ledanek]

thanks Big_Daddy for that inspirational build post.
I'm the type that goes by pictures...I don't understand all the reasoning behind the build, I just want it to start on the "first start."

I'm about to add three 120mm Yate Loon D12SL-12 White LED side fans for my Stacker 830 AND I will probably base my build on your wirings...oh wait, I don't have fan controllers.

any suggestions? I don't mind hummings from fans...I play/work with headphones and PC is in a play/work room very far from anyone's bedroom.

advance super-thanks

[vinister]

dont wire your fans in series. You'll either burn out your motherboard or the controller and/or, at the very least, they won't even spin. Remember that just because the wires go from one fan to the next in a chain, it doesnt mean its wired in series. Series is when you use the black wire (ground) of one fan and hook it to the red wire of the next.

If you simply run the wires to the first fan, then jump all the wires (color for color) to the next fan, and to the next, etc etc, it is still in parallel, even though all the wires aren't coming to the 'same spot'.

I had to mention this because from your diagram of 'series' wiring, you don't show the connections, which is the only place where it might become 'series'. As per your 'series' diagram, if you connect the reds to reds, and blacks to blacks, then that is not series at all, it is perfect parallel.

[emoners]

great info

[LuckyNV]

dont wire your fans in series. You'll either burn out your motherboard or the controller and/or, at the very least, they won't even spin. Remember that just because the wires go from one fan to the next in a chain, it doesnt mean its wired in series. Series is when you use the black wire (ground) of one fan and hook it to the red wire of the next.

If you simply run the wires to the first fan, then jump all the wires (color for color) to the next fan, and to the next, etc etc, it is still in parallel, even though all the wires aren't coming to the 'same spot'.

I had to mention this because from your diagram of 'series' wiring, you don't show the connections, which is the only place where it might become 'series'. As per your 'series' diagram, if you connect the reds to reds, and blacks to blacks, then that is not series at all, it is perfect parallel.

Thanks for clearing that up, my high school physics escaped me
Was a bit confused, I use the pass through connections, I thought it was series for a moment, but the fans still act like they do if plugged into the controller singly, must be parallel then. thanks again

[XS_RoB]

Hope this Helps - It was taken from this Post.

http://www.xtremesystems.org/forums/...ht=wiring+fans

L8r,
RoB

[Cpl Ledanek]

Hope this Helps - It was taken from this Post.

http://www.xtremesystems.org/forums/...ht=wiring+fans

L8r,
RoB

wow, that should be a sticky!
Awesome!

[emoners]

just a noob question...why only 1 yellow wire?

[Serpentarius]

yellow wire is for rpm .. just one is enuf? or having multiple rpm signals in one cable is dangerous?

[emoners]

yellow wire is for rpm .. just one is enuf? or having multiple rpm signals in one cable is dangerous?

that was what i was thinking...any effects on joining them rpm sensors? wouldn't it be nice to know if all 3 fans are running the same speed?

[Serpentarius]

it wont be the same ... the rpm will drop and increase slightly depending on the situation

i recall if the all the yellow wire of them is joined, the rpm might give triple results ... to get average .. might need some slight transistors to do the job
maybe someone can further clarify

[vinister]

I can clarify. the yellow wire sends out a pulse wave, the frequency is double (or half, cant remember) the actual RPM, and your motherboard (or fan controller) does the math to give you a readout. Connecting them would likely damage something, or at the least, give you a very erratic readout. Theoretically if the fans were spinning at the exact same speed, and completely in sync, and were started at the exact same moment, then the pulse waves might be in phase... but that is impossible unless the fans blades are physically connected. There will always be a variance in speed between the fans, so you really need a seperate circuit to read each speed individually.

I hooked up a few of my fans to a scope, and the waveforms are already so noisy, its a wonder your motherboard can even give you a steady readout with one fan, especially as the drive voltage is reduced. The motherboard must have a schmitt trigger on the input to tell the pulses from the noise. Even if you designed a circuit to average the speed signals, I doubt it would trigger properly, I would be surprised to see it ever work.

[Cpl Ledanek]

so, if I'm happy with their
---air movement/ or intended purpose
---noise doesn't bother me
---not too concern controlling speed & voltage individually
...I can simply connect them per illustration and connect them directly to a free molex to the PSU?...

that is how I got them right now and I'm quite surprise that the PSU's fan noise is just overwhelming the other noises (if any) from my other parts.

I even took off the side door while still powered and ran the fans separated from the case....to see if I can isolate which fan is making more noise. Besides a minor humm, its fairly quiet...the noise from the PSU fan is still louder.

thanks for all the education.

[vinister]

Another good tip is to make sure all your fans are the exact same brand and model #. You can even open up your PSU and change the fan so they all match. The purpose of this is to keep all the noise in the same frequency band, reducing the perceived loudness quite a bit.

If you pull out a 120mm fan, hook it up, and just listen to it on its own, you can experiment to see what's making it loud. Holding it up in the air, almost any 120mm fan is dead silent, because there is little friction on the blades, the air moves very smoothly from one side to the other, with very little effort by the fan.

Put some mesh behind the fan, and instantly it gets a bit louder. You get the noise of the air moving through the mesh, and the extra noise from the motor because it has to work harder.

Put the mesh in FRONT of the fan, and now you're really loud. For whatever reason, stuff on the intake side of the fan affects its volume output 10 times more than stuff on the exhaust side. Try it for yourself, you'll be amazed.

So naturally, after hearing that, you will be chopping out all the mesh from both sides (especially intake) of all your fans. If you need some kind of mesh, you can make it much quieter (and more effective) by spacing the fan away from the mesh and using a shroud. The distance of the fan to the mesh should be at least one-half of the diameter of the fan for best results.

[emoners]

i'm guessing same goes for fan grills right?


there goes my fingers...

[silverphoenix]

just to clarify make sure your fan controller provides enough amperage to power all those fans. I'm sure it will be fine, My sunbeam can control a massive 20 watts per channel but some controllers are weaker.