5 fans 2 headers.

[CosminCC]

Hello there.
I have 5 fans on my system but only 2 headers on the mobo. One 3 pin and one 4 pin. I ordered already the Akasa AK-CBFA03-45 Flexa FP5 PWM Splitter. My question is: if i'll connect the 4 pin of the splitter to the 4 pin header of the mobo and the molex of the splitter to the psu then my mobo will can control the speed or the fans will be running at 100% because of the molex?

 

[BonzaiDuck]

Assuming you are only using 4-pin PWM fans, and there are enough ports on the splitter, that would be an ideal solution.

PWM only requires a signal to a PWM fan to control the speed. Getting power from the PSU directly takes a burden, no matter how minor, off the motherboard. So, yes, you will be able to control the speed for PWM fans that way with only the signal connection to a mobo PWM port.

If you plan on using any 3-pin fans, I can tell you what you can do without purchasing a controller using only the available port. Are you going to use any 3-pin voltage-controlled fans?

 

[CosminCC]

The splitter is 4 pin for the mobo 4 pin header but all my fans and the splitter connectors for fans are 3 pin..

 

[BonzaiDuck]

The splitter is 4 pin for the mobo 4 pin header but all my fans and the splitter connectors for fans are 3 pin..

You have two ports. Please correct me, but I want to assume that you can use either 3-pin or 4-pin fans on the CPU port. that is, system determines itself whether to control by voltage or control by PWM signal. You just have to set it to one or the other for that fan plug in BIOS -- if your BIOS allows it. But I would think most mobo CPU_FAN ports are thermally-controllable through the motherboard for either 3-pin or 4-pin.

I don't think the 4-pin splitter will allow you to do anything more than run them at full speed, unless -- for being the "lead" fan in the PWM string, a 3-pin fan would be detected for voltage-control operation. You can try it.

I would just separate my 3-pin fans into two groups, maybe "CPU" and "System," so that adding up the amperage to fans in any group would show a total less than 0.80Amps. You could draw more, but that limit would allow for maybe 3+ 0.20A fans.

Choose the yellow tach wire for the one fan in each group you want to monitor. Connect ground and power leads in parallel, so you end up with a single 3-pin plug on a wire, with the chosen tach wire and the power connections. The other tach leads should simply be left out of any connection.

I solder the connections, and wrap them in self-adhesive rubber automotive hose-bandage tape.

 

[Paperdoc]

The issue is that a true 4-pin fan header that actually uses PWM Mode for controlling fans can NOT control any 3-pin fan. It can only control 4-pin fans. You say all your fans are 3-pin, and the only way to control those is using Voltage Control Mode.

Do not worry about the four output arms of your Akasa splitter that have only 3 pins. They are supposed to be that way. They are all missing only Pin #3, which is the one that connects the speed signal output from each fan to the mobo header. But the header can only handle ONE speed signal, so only ONE output arm of the splitter has its Pin #3 to send that signal back. By the way, I would label that unit a Hub, not a splitter. The difference? A splitter only connects all its fans in parallel to the power supplied by the mobo header, and that is limited to no more than 1.0 amps total load. A Hub, on the other hand, connects all its fans only to the PWM signal it gets from Pin #4 of the mobo; it actually supplies the power for all its fans directly from the PSU output that it plugs into, and that can supply much more amperage than a mobo header can.

Now, to give you a complete answer, we need you to tell us exactly what mobo you have - maker and exact model number. The problem is that many mobo makers have taken to using 4-pin headers that actually operate only in 3-pin Voltage Control Mode, and some do not do that. If we can look up your mobo's manual we can tell you exactly what can be done to power and control all five of your 5-pin fans. By the way - IMPORTANT - when you say you have 5 fans total, is that all of them including the CPU cooler system, or do you have five case ventilation fans PLUS a CPU cooler in addition?

 

[BonzaiDuck]

The issue is that a true 4-pin fan header that actually uses PWM Mode for controlling fans can NOT control any 3-pin fan. It can only control 4-pin fans. You say all your fans are 3-pin, and the only way to control those is using Voltage Control Mode.

Do not worry about the four output arms of your Akasa splitter that have only 3 pins. They are supposed to be that way. They are all missing only Pin #3, which is the one that connects the speed signal output from each fan to the mobo header. But the header can only handle ONE speed signal, so only ONE output arm of the splitter has its Pin #3 to send that signal back. By the way, I would label that unit a Hub, not a splitter. The difference? A splitter only connects all its fans in parallel to the power supplied by the mobo header, and that is limited to no more than 1.0 amps total load. A Hub, on the other hand, connects all its fans only to the PWM signal it gets from Pin #4 of the mobo; it actually supplies the power for all its fans directly from the PSU output that it plugs into, and that can supply much more amperage than a mobo header can.

Now, to give you a complete answer, we need you to tell us exactly what mobo you have - maker and exact model number. The problem is that many mobo makers have taken to using 4-pin headers that actually operate only in 3-pin Voltage Control Mode, and some do not do that. If we can look up your mobo's manual we can tell you exactly what can be done to power and control all five of your 5-pin fans. By the way - IMPORTANT - when you say you have 5 fans total, is that all of them including the CPU cooler system, or do you have five case ventilation fans PLUS a CPU cooler in addition?

All true. Even so, if he's using a PWM [hub, splitter, etc.], he could not control 3-pin fans on it. They would all run full-bore, as far as I understand or what I'd seen and read. the PWM fans could be voltage-controlled through a 4-pin port that provides only voltage control. I'd recommend then one fan, one port. I'm thinking he could either solder together a parallel connection between 3 and 4-pin fans to exclude doing anything with the PWM signal wire. But unless the splitter is only a parallel wiring, I wouldn't mess up a PWM fan as part of that harness. I suppose you could simply solder in 3-pin plugs, connect a PWM and a couple 3-pin fans, and impose "DC" or "Voltage control" in the BIOS.

In my case, I have a new board that allows configuration as "PWM" or either "DC"/"Voltage controlled" in the BIOS. I could only hope that OP has at least that feature for his board with two ports. Otherwise, he either needs a 3-pin splitter, a soldering iron and coil of solder, or a mix of the two fans. He should really be able to do this with the fans he has, though.

 

[Paperdoc]

Bonzai Duck is correct on most of this. That is why I asked for specifics about the mobo - so we can check for sure what it can do for you. But I realize we need another bit of info, OP. Exactly what fans do you have? Maybe they were part of your case, and you'll need to tell us the case details. From those we probably can find the current draw for each fan. IF it turns out your mobo can deal with 3-pin fans properly, that can tell us whether all those fans can be connected to one header or not. And if so, what splitter you would need. The Akasa Hub you have ordered will not do it because it does not connect the power leads from the mobo header to any of the fans.

Although you can make your own connections without using a purchased splitter, by doing your own soldering as BonzaiDuck suggests, I suspect you are more interested in the method that avoids soldering.