Phanteks PWM hub setup

[Oriaz]

Hey guys,

Pretty sure I am doing something wrong, so wanted to check it out here!

I just finished building a new hard-tube watercooled setup with 2 radiators (top and front) in a Phanteks Enthoo Primo case. The case comes with PWM hub hidden around the back in the cable management area, and some pretty terrible instructions!

I have connected a 4-pin cable from the CPU Header on the motherboard (MSI X99 SLI Krait Edition) to the indicated connector on the PWM hub. I have also connected the 12v power supply. I have then connected a 3-way splitter to the 3x Vardar fans on the top radiator to another of the PWM hub connectors, and there were 3 case-fans already connected to hub when I got the case (2 of them are at the front, and I am using them to cool the font radiator).

This is how it looks:

My problem is that the system doesn't seem to detect any CPU fan, just "system" fans as you can see here:

And when the temps are low, rather than reducing the speed of all 3 fans on the top radiator, it just seems to randomly stop one of them, so that 2 of the 3 fans are spinning, and one is idle.

I'm trying to figure out how to connect everything so that I can set a temperature profile that actually works properly! Or is it better to ignore the hub, and just connect everything individually to the motherboard headers?

Thanks for any help, hopefully it made some sense
Cheers, Ori

 

[Tealc]

See that white header with no connection? Try bunging one of the fans on it. This white header is the only header which sends a tach signal back to the motherboard via the 4 pin connector you have connected.

Wouldn't it be easier to connect your 3 Vardars to the 3 vacant spots on the hub if you took the splitter off?

You will also need to make sure your BIOS or fan control software is actually working in PWM mode. If it isn't then the PWM hub will not work. The hub works fairly well at regulating a DC voltage off a PWM signal and is ideal for 6 fans.

From the graph you should see 5v-12v through the 20%-100% duty cycle range.

 

[Oriaz]

I did try that originally, but then there was a cryptic sentence in the user-guide that said "Y-splitter should not be connected to FAN 1", which I assume also applies to my 3-way splitter, so I put it somewhere else.

Maybe I'll try again and see.

Thanks for the reply,
Cheers

 

[Oriaz]

Ahh, I can try to connect the fans individually, problem is that only one of them has a cable long enough to reach, so it's purely through convenience that I was using the splitter . Think I have 1 x extension from an old Noctua fan somewhere though that I can use

 

[Tealc]

I did try that originally, but then there was a cryptic sentence in the user-guide that said "Y-splitter should not be connected to FAN 1", which I assume also applies to my 3-way splitter, so I put it somewhere else.

Provided your splitter only has one tach line from its fans then it will be fine. Check the three connectors at the fan end and check for a wire in position 3, only one of them should have it.

I guess Phanteks didn't want people trying to squirt multiple tach signals down the line and making a mess of things.

 

[doyll]

As Tealc said, the white fan is the only one that can receive a RPM signal to be sent to motherboard fan header.
Could you plug the radiator fan that will reach to the white header and leave the other two on the splitter?

 

[Oriaz]

Thanks for the advice guys,

So I've just plugged one of the fans into the white connector, and managed to plug the other 2 into two separate connectors on the hub, using extensions. So, all 3 fans are connected to different connectors now. The problem is that all 3 fans have 4-pin connectors, and all of the points on the PWM Hub (including the white one) are 3-pin.

So far, it seems to have worked I think. Speedfan now recognises a CPU fan, Fan 4 and Aux1 Fan. But I do still seem to have the issue where it shuts down fans, rather than slows them all down. When I first turned the PC on, my CPU was at 35 degrees, and only 1 of the 3 fans was spinning. I booted WoW and it went over 50 degrees, and then all 3 started spinning!

Now I just need to figure out the best way to control them I guess. I can do it via the BIOS, but not sure if something like speedfan is better.

Thanks again for the help, I'll keep fiddling to get this right before I start working on the overclock

Cheers

 

[Tupro]

Thanks for the advice guys,

So I've just plugged one of the fans into the white connector, and managed to plug the other 2 into two separate connectors on the hub, using extensions. So, all 3 fans are connected to different connectors now. The problem is that all 3 fans have 4-pin connectors, and all of the points on the PWM Hub (including the white one) are 3-pin.

So far, it seems to have worked I think. Speedfan now recognises a CPU fan, Fan 4 and Aux1 Fan. But I do still seem to have the issue where it shuts down fans, rather than slows them all down. When I first turned the PC on, my CPU was at 35 degrees, and only 1 of the 3 fans was spinning. I booted WoW and it went over 50 degrees, and then all 3 started spinning!

Now I just need to figure out the best way to control them I guess. I can do it via the BIOS, but not sure if something like speedfan is better.

Thanks again for the help, I'll keep fiddling to get this right before I start working on the overclock

Cheers

you can use 4 pin fans in a 3 pin without issue, the 4th pin is just for PWM signal anyway, which your hub is doing itself

check the MSI site for your mobo too, some of them have software for controlling fans instead of going into bios.. otherwise i would stick with speedfan

 

[doyll]

The difference between 3-pin variable voltage control and 4-pin PWM control is not complicated.
Variable voltage does just that .. vary the voltage (approx 4-12v) to control fan speed. PWM control uses 4th pin to send a signal to a PWM control circuit in the fan that pulses the constant 12v power to control fan speed.

The Phanteks PWM fan hub is not a PWM fan hub. It is a PWM controlled variable voltage fan hub. It uses the PWM control signal to vary the voltage going to the fan. It does not use PWM pulsed 12v.

Here is a better graph of Tealc's testing of Phanteks PWM hub

Here are Tealc's oscilloscope images and explaination

At higher loads it was noticed that some voltage spikes occurred with the switching of the circuit, this may cause premature failure of the circuitry and produce extra heat. The image below shows a nice smooth trace with 4 fans, then the lower shows some spikes with 11 fans.

 

[JJJ]

Following your explanation doyll of 3/4 pin fans, I understand the difference. However when would you want to use one over the other?

 

[doyll]

While PWM power/control has many advantages over variable voltage in general they make little to no difference in computer fans. It has much more to do with your needs and resources are, like what control sources you have, number of fans needing control, how many fans are same and need to run same speed versus different fans running at different speeds, etc.

Advantages of PWM or are they?
Less energy used .. .. so what? We are talking about motors that are only 1-4 watt

• No neat generated .. .. so what? The heat generated reducing voltage for variable voltage isn't much .. after all it's only 1-4 watt.
• More power at lower speeds .. .. so what? Most decent variable voltage fans idle below 600rpm anyway.

A single PWM controlled header can be used to control approx. 8 fans if their 12v power is directly from PSU .. versus .. a single variable voltage header can only control a maximum of 12 watts (wattage rating of most fans is about half of what they draw starting up) so only 1-5 fans maximum).

In industrial applications like motors used in cordless drills, milling machines using variable speed and high power levels the advantages of PWM control make a big difference in ability to control motor speed and efficient use of energy used. PWM in a cordless drills not only gives us way more torque but also much longer battery life. In things like milling machines, shapers, etc. it also allows much better control of consistent rpm control (stable rpm regardless of load). But there is little difference in computer fan applications only using 4-7 fans. The only time I can think of that is would make a significant difference is a big liquid loop running lots of fans on big radiators .. like 2x 480 radiators running 8 fans on a single control.