Fan splitter PWM problem

[iKatoz]

I bought a 5-way PWM fan splitter (this: http://www.amazon.co.uk/Akasa-AK-CBFA03-45-Flexa-Splitter-Cable/dp/B005EKU5CO/) and now I can't control my fans.

Before I had a Y splitter (3 pin) and I was be able to control the speed of the fans without problems, now AI Suite show me this screen:

 

Can someone help me?

Thanks

[UnlimitedTMD]

mkay, nice mate

[Bittenfleax]

What's wrong? Nobody can help you if you're not explaining anything...

^

[iKatoz]

I pressed the button to publish the post instead of the preview :C

[Pandora]

I pressed the button to publish the post instead of the preview :C

press the edit button

[EmeraldFlame]

Do you have both the molex, which should be plugged into the PSU and is providing additional power, and the 4 pin, which should be plugged into the MB and is supplying the RPM readout/pwm signal, plugged in? If you plug in just the molex power, all the fans will work, they will just run at full speed and not give you any control. You need both plugged in.

[0x1e]

I'm thinking what he is saying is,

 

With a Y splitter he could control the fans, as the second fan would just copy the first one.

Now with the 5 way splitter he can't control any of them. It's not detecting the fans.

 

Are your fans turning on at all with the 5 way splitter?

[iKatoz]

Do you have both the molex, which should be plugged into the PSU and is providing additional power, and the 4 pin, which should be plugged into the MB and is supplying the RPM readout/pwm signal, plugged in? If you plug in just the molex power, all the fans will work, they will just run at full speed and not give you any control. You need both plugged in.

Yes, there is also one of 5 cables that read the RPM of one fan 

 

I'm thinking what he is saying is,

 

With a Y splitter he could control the fans, as the second fan would just copy the first one.

Now with the 5 way splitter he can't control any of them. It's not detecting the fans.

 

Are your fans turning on at all with the 5 way splitter?

Yes, I do not know how fast they spin, definitely not at the minimum speed

 

I forgot to say that they are all 3 pin fans. Before I control 2 fans whit the Y splitter connected to the motherboard and the other two whit the integrated fan controller 

[EmeraldFlame]

I forgot to say that they are all 3 pin fans.

 

Ahh it makes sense now. Your fans aren't compatible with a setup like this.

3-pin and 4-pin fan control works differently.

In 3-pin fan control the controller varies the voltage it sends over pin 2 to the fan which makes it run at different speeds. 12v is full speed, so if you want 50% it sends 6v instead.

With 4-pin fan control the controller sends a constant 12v over pin 2, but sends an on/off signal over pin 4 which tuns the motor on and off at very fast speeds (think strobe light but for a motor). In this way to vary speed it changes how long the fan is on, 100% is always on whereas 50% means it is only on half the time.

You'll notice that the MB side connector that you bought only has pins 3 and 4 (speed sensor and on/off signal). It does not have pins 1 and 2 (ground, positive). This means it is getting it's power from the PSU connector instead, which is going to give you a constant 12v that you can't control. 4-pin fans would work, 3-pin fans will run but at max speed with no control.

To make this work, you need 4 pin fans. Alternatively, you could get a 3-pin splitter, but running 5 fans off one MB header may draw more power than what the MB can supply and fry the header depending on the fans.

Hope that makes sense to you.

[iKatoz]

Yeah, it make totally sense, I cannot belive I didn't think of that.

If I buy this it should be fine, right? http://noctua.at/en/na-syc1.html

[EmeraldFlame]

Yeah, it make totally sense, I cannot belive I didn't think of that.

If I buy this it should be fine, right? http://noctua.at/en/na-syc1.html

 

Yup, that should work properly with both 3 and 4 pin fans. Most MB headers can supply 1A @ 12V (although this does vary some from MB to MB) and that is enough to run 2 of almost any fan safely, so you should be good.

[iKatoz]

Thanks for the help, I will buy this splitter