Question PWM Fan + Fan Controller confusion

[MarioRud]

Hi all! Just making this thread because I'm a bit confused in regards to PWM fans connecting to a fan controller.

I'm currently looking to build a Mini Itx PC. I've settled on the NZXT H200i which comes with a fan hub. I'm not interested in water cooling and I want to buy some be quiet! Silent Wings fans for intake and exhaust. From what I understand PWM fans have 4 pin connectors, but the fan controller hub has 3 pin connectors and 4 pin shouldn't be connected to 3 pin.

Does this mean I will just have to connect the fans directly to MOBO? (2 intake, top exhaust, rear exhaust).
Not quite sure what PWM does exactly but what would be ideal for me is that all fans only spin at speed depending on the temp inside the case rather than full speed at all times.

Sorry if this is a rookie question, haven't built anything in a long time so I'm a bit rusty when it comes to this stuff.
Any help is appreciated, thanks!

 

[RememberThe5th]

Which motherboard do you have?

Almost most of newer motherboards support DC control on 3pin you can split the 4pin PWM for your case fans (1A is limit to most motherboards on fan controller, some are exceptions, for instance one of your fans use lets say 0.2A you can connect 4-5 on one).

 

[Paperdoc]

For what you want, I would suggest you ignore the case's Smart Device board regarding fan MOTOR connections. IF you buy fans that also have RGB lights in their frames, you MIGHT want to connect the RGB lighting cables via the Smart Device, but not the fan motor cables.

There are two main types of fan motor systems. The older one with 3 pins can only be controlled by varying the voltage supplied to it on Pin #2. In the newer PWM design, that supply is always 12 VDC but there is a new PWM signal sent out on Pin #4. The fan itself contains a small chip inside that uses that new signal to modify power flow from the 12 VDC source through the motor, thus altering its speed. So the PWM system is just a method of controlling a fan speed. As it happens, the design of these has a backwards compatibility feature. If you plug a 4-pin fan into a 3-pin header that is using the older Voltage Control Mode, that still CAN control the fan speed.

The terms "3-pin" and "4-pin" can cause confusion when you use a Splitter or a Hub to connect many fans to a single mobo header. The root of this is that any header can only deal with the speed signal sent back to it by ONE fan. So any Splitter or Hub will only send to its mobo host header ONE fan's speed and ignore all the others. The easiest way to do that is to omit Pin #3 (the speed signal pin) on most of the output connectors from the Splitter or Hub. So some people look at a header that has space for 4 pins but is missing Pin #3 in the line, and call it a 3-pin fan header. It is not. On the other hand, that Smart Device board in the case could be doing things a different way. Although it MUST have a PWM control signal from a mobo header to work, it MAY be converting that info into the older Voltage Control Mode and putting out signals to its fans in that older way. But as I said above, a new PWM-type fan connected to this signal system still IS controlled.

But really, IF you have enough mobo headers to connect all the fans you plan to them, that is better than using the Smart Device. What you want - all fan speeds controlled by the mobo according to workload as determined by temperature measurements - is the normal "automatic" control that mobo headers do. In fact, Splitters, Hubs and that Smart Device depend on getting exactly that signal from a mobo header to do their fan speed control work.

So we can be sure to get all the details right, tell us exactly what fans you are buying - and how many of them - for case ventilation. IF you are also replacing the CPU cooler system or just its fans, tell us about them separately. Then tell us what maker and exact model number is your mobo? We can look up the details and advise how to get the control you want from the mobo without using the Smart Device unit.