Question Case fan question

[getting old]

Apologies in advance, i've built all my pc's since the 80's, a time when you had to be nerdy Now i find myself struggling to keep up with technology, i've become a dinosaur😕. I've searched till blue in the face and i can't find an exact answer.
I have three 120mm cit case fans wired with both Molex pass through and 3-pin.
In previous builds I've just used molex connectors plugged into the psu. 3 and 4 pin to the motherboard (in my day it was known as the mainboard😄) are new to me (I usually make a new pc 8-10 years!).

basically my question is: my MB doesn't have enough headers for my fans. If I daisy chain two of the cit fans via the pass-through molex connectors and plug in one of them via 3 pin to MB (not connected to psu) will both fans change speed with the reading from the plugged in fan.

I hope i've been clear enough?

 

[Lutfij]

Welcome to the forums, newcomer!

Can you please pass on the model to your CiT fans? If the fans came bundled with the case, then passing on the model of the CiT case would help us two fold.

Some fans have a single connector and if your fan has two connectors it's probably that they are for the ARGB/RGB. If they are DC fans with a Molex connector, then you can't use them both, only one can be hooked up(either the PSU or the motherboard).

If you have a PWM hub or controller, then running a 3pin fan will result in said fans to run at full blast.

(in my day it was known as the mainboard😄)
I've been building PC's since 2001, I know them as motherboards.

 

[SkyNetRising]

I have three 120mm cit case fans wired with both Molex pass through and 3-pin.
my MB doesn't have enough headers for my fans.
If I daisy chain two of the cit fans via the pass-through molex connectors and plug in one of them via 3 pin to MB (not connected to psu) will both fans change speed with the reading from the plugged in fan.

Please list model name of your motherboard and
show photos of connectors on your fans.
(upload to imgur.com and post link)

What you're describing would look like this.
If it looks different, then we definitely need a photo.

Spoiler

 

[getting old]

Welcome to the forums, newcomer!

Can you please pass on the model to your CiT fans? If the fans came bundled with the case, then passing on the model of the CiT case would help us two fold.

Some fans have a single connector and if your fan has two connectors it's probably that they are for the ARGB/RGB. If they are DC fans with a Molex connector, then you can't use them both, only one can be hooked up(either the PSU or the motherboard).

If you have a PWM hub or controller, then running a 3pin fan will result in said fans to run at full blast.

(in my day it was known as the mainboard😄)
I've been building PC's since 2001, I know them as motherboards.

Thank you.
The case is a fractal design and came with two 120mm white led fans at the front, both have single 3 pin plugs. For positive ventilation I bought a white led corsair 140mm fan for the bottom (also single 3 pin plug) and three cit 120mm with red led for top x2 and 1 rear (white for inlet and red for exhaust seemed like a good idea at the time, a decision I may regret if I want the led's off when they get annoying). That said, they were on clearance and cost less than £2 each, bargain! The cit ones came with molex and 3 pin as shown in SkyNetRising's reply.

I like the term motherboard, much softer and less technical than mainboard.
My first build was an AMD x586 processor with a massive 4 Megabytes of ram running dos based windows 3.11. Everything had to be set up with jumper switches. Motherboard, hard drives and floppy drive (no cd back then!)
Plug and Play is a godsend....

 

[getting old]

Please list model name of your motherboard and
show photos of connectors on your fans.
(upload to imgur.com and post link)

What you're describing would look like this.
If it looks different, then we definitely need a photo.

Spoiler

 

[getting old]

That's exactly what the cit fans have.
The MB is Asus tuf gaming B550 plus and has 3 case fan headers and higher rated AIO pump header.
What i'm struggling to ask is if I connect two fans via molex like this....



....can I plug one of the 3 pin plugs into a MB header and (crudely) control fan speed with the dc setting in bios (as opposed to pwm, I have the choice)? I realise only one fan will be monitored but since they're together anyway both should be controlled with the same voltage, or is my thinking wrong?

 

[SkyNetRising]

The case is a fractal design

Is it Focus G ?

and came with two 120mm white led fans at the front, both have single 3 pin plugs.
I bought a white led corsair 140mm fan for the bottom (also single 3 pin plug)
and three cit 120mm with red led for top x2 and 1 rear

The case doesn't need 6 fans.
Two intake fans in front and one exhaust fan in rear - this is plenty airflow.

You do not need a bottom fan.
And you do not need top fans (unless you're putting AIO radiator in there).

The MB is Asus tuf gaming B550 plus and has 3 case fan headers and higher rated AIO pump header.

The board has 3x CHA_FAN headers
One AIO_PUMP header and
2x CPU_FAN headers.
So - 6 headers total.

If you abandon your idea about excessive number of fans, you have plenty of fan headers there.

What i'm struggling to ask is if I connect two fans via molex like this....
....can I plug one of the 3 pin plugs into a MB header and control fan speed with the dc setting in bios?

You can, if you must.

 

[getting old]

Is it Focus G ?

The case doesn't need 6 fans.
Two intake fans in front and one exhaust fan in rear - this is plenty airflow.

You do not need a bottom fan.
And you do not need top fans (unless you're putting AIO radiator in there).

The board has 3x CHA_FAN headers
One AIO_PUMP header and
2x CPU_FAN headers.
So - 6 headers total.

If you abandon your idea about excessive number of fans, you have plenty of fan headers there.


You can, if you must.

Yes It is a Focus G, a case i'm very impressed with.
It cost around £50, came with all necessaries including cable ties and best of all well made, no sharp edges at all. It's difficult these days to find a case with drive bays, I'm amazed they can do it for such a low price. (I have no affiliation to the company. Feel free to remove the relevant parts if they break forum rules).

The case will be used in a dusty atmosphere so my thinking was additional magnetic mounted filters and more fans to compensate for additional load?

Sorry for not mentioning CPU_FAN headers, I was more focussed on CHA_FAN ones.

Thank you for the advice. As a newbie here I didn't realise I could post pics, that one pic got me the answer to the question I was asking. Lesson learned!

 

[Paperdoc]

Hypothetically what you propose will work. BUT there are IMPORTANT limits you must take into account. I've been at this a while so I grasp some items you noted that others may miss.

Your fans are "LED fans", you say. This was the first type of fan that included lights in the frame. Those LED's in the frame are merely connected in parallel with the fan motor, and there is NO second separate cable for the lights. They draw power from the same lines that feed the motor, so their power is from the mobo fan header (IF that it where you plug in the fan). That means that the max current draw from such a fan is higher than a similar fan with no lights. Each fan has only one colour of light in it, and its brightness varies as the Voltage supplied to the fan by the header is reduced to slow it down. However, since your fans all are connected to a 4-pin Molex power output from the PSU, you will not have seen that because they always receive a fixed 12 VDC supply. Your fans are NOT either of the more current types: plain RGB or more complex ARGB.

The limiting factor here is that all mobo fan headers are limited to a max 1.0 A current draw for ALL the fans connected to that one header. See your mobo User Manual, p. 1-2. So IF you connect more than one fan to a header this limit is important. The more common way to do this is with a Splitter, but you propose using the existing 2-sided Molex male / female connectors on your fans that allow a "daisy chain" connection system. That really has the same effect - all the fans in that chain are getting their power from the header that the FIRST fan draws from via the 3-pin female connector. You may not be able to find this spec from a web page for those fans, but each fan should have a label that shows its max Voltage and Amps rating. (IF they show only Watts, Watts = Volts x Amps, and the max Voltage is always 12.) So identify the max AMPS one fan can draw, and add up that spec for every fan in ONE chain. The total can NOT exceed 1.0 A for any chain connected to one mobo CHA_FAN header. You have 3 three such headers on your mobo, so you might be able to connect, say, two fans per chain in a total of three chains, one for each CHA_FAN header, with no excess Amps issue.

Other than that limit issue, a few points FYI. Your fans are 3-pin - that is, each fan motor has 3 wires to it from a female connector, but of those only two wires continue on to the 2-sided 4-pin Molex connector. Those two wires are the Ground and +12 VDC lines. The third wire from each fan is the speed signal line that takes a pulse train from the motor back to the host header on the mobo. So with the system you propose - first fan to a mobo CHA_FAN header using the 3-hole female connector, and then another (one or two) added on via the 2-sided Molex connectors to complete the chain - the speed of the first fan WILL be sent to the mobo, but not the speed signal of the added ones. This is just right - the header can only deal with a speed signal arriving from one fan, anyway. So the speed of the added fans of each chain will never be "seen" anywhere. This does NOT affect ability to control fan speeds - that info is NOT used by the mobo header to accomplish control. Of course, in this scheme there is NO connection of any Molex connector to an output from the PSU.

Control of the speed of this fan type is done solely by varying the Voltage supplied to the fan by Pin #2 of the header. It can range from +12 VDC for max speed down to about +5 VDC for min speed without stalling. If you connect 2 or 3 fans in one chain to a header, they are in parallel and all of them will receive this supply and do exactly the same thing, so all are speed-controlled.