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Help with PWM fan splitter

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  • Fan
  • Speed
  • Systems
  • Motherboards
Last response: in Systems
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September 11, 2014 6:16:14 PM

I have 2 Akasa 5 fan PWM splitters to control the speed of my 7 Corsair SP120 High Performance PWM fans. I have 4 plugged into one and 3 on the other. I have the power plugged directly in to a power supply and the PWM connector on my motherboard's case fan port. When I go to adjust the speed in SpeedFan, it does nothing and continues to run at 100%. I've tried other pwm fans on that port with SpeedFan and they adjust the speed accordingly. Furthermore, if I simply remove the pwm connector, the fans still run at 100%. I have also tried doing it though the motherboard's BIOS, and that didn't work either. For your information I have the Crosshair V Formula-Z motherboard with latest bios. Any help to get this working would be great.
Thank you.
I also emailed Akasa about this issue, so if you solve it before you guys do, I'll post the solution on here for anyone else having this problem.

More about : pwm fan splitter

a c 519 V Motherboard
September 11, 2014 6:22:32 PM

Looking at the enlarged pic of the 4 pin PWM female connector end (the end that plugs into the MB header), it doesn't appear that all 4 pins are wired. It looks like just the +12V and neg is wired. Is that the way yours is?
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a c 243 V Motherboard
September 11, 2014 6:36:02 PM

I have never had any luck with cable splitters. I'd suggest this as an alternate. I have three of them .... and they work on both PWM and DC headers.

http://www.phanteksusa.com/products/phanteks-fan-hub

Unless you exceed 1 amp, you don't even need the auxillary power connector.
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September 11, 2014 6:42:01 PM

clutchc said:
Looking at the enlarged pic of the 4 pin PWM female connector end (the end that plugs into the MB header), it doesn't appear that all 4 pins are wired. It looks like just the +12V and neg is wired. Is that the way yours is?


The two wires on the plug that connects to the motherboard are the one after the clip and the one at the end of the clip.

JackNaylorPE said:
I have never had any luck with cable splitters. I'd suggest this as an alternate. I have three of them .... and they work on both PWM and DC headers.

http://www.phanteksusa.com/products/phanteks-fan-hub

Unless you exceed 1 amp, you don't even need the auxillary power connector.


Does that come with any splitter or do I have to get them myself? Also it would suck if I had to resort to that because I got 6 new sp120 just for PWM and I already had the non-pwm ones...
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a c 519 V Motherboard
September 11, 2014 6:47:11 PM

Stardust342 said:
clutchc said:
Looking at the enlarged pic of the 4 pin PWM female connector end (the end that plugs into the MB header), it doesn't appear that all 4 pins are wired. It looks like just the +12V and neg is wired. Is that the way yours is?


The two wires on the plug that connects to the motherboard are the one after the clip and the one at the end of the clip.



Then that's why it isn't working. The fans will run at full RPM all the time. There is no PWM control w/o the PWM wire and no tach feedback w/o the other wire.
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September 11, 2014 6:54:11 PM

clutchc said:


Then that's why it isn't working. The fans will run at full RPM all the time. There is no PWM control w/o the PWM wire and no tach feedback w/o the other wire.

Are you sure it doesn't have the pwm wire? I do get a rpm reading in bios and aida64...
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a c 243 V Motherboard
September 11, 2014 6:57:31 PM

Stardust342 said:
clutchc said:
Looking at the enlarged pic of the 4 pin PWM female connector end (the end that plugs into the MB header), it doesn't appear that all 4 pins are wired. It looks like just the +12V and neg is wired. Is that the way yours is?


The two wires on the plug that connects to the motherboard are the one after the clip and the one at the end of the clip.

JackNaylorPE said:
I have never had any luck with cable splitters. I'd suggest this as an alternate. I have three of them .... and they work on both PWM and DC headers.

http://www.phanteksusa.com/products/phanteks-fan-hub

Unless you exceed 1 amp, you don't even need the auxillary power connector.


Does that come with any splitter or do I have to get them myself? Also it would suck if I had to resort to that because I got 6 new sp120 just for PWM and I already had the non-pwm ones...


It has 6 outputs, one PWM input and six 3-pin outputs. It comes with:

(1) Power Cable
(1) PWM Input cable
(2) splitters.

It can take up to 11 fans

I have never seen anyone use it on PWM tho cause it gives PWM control to 3 pin fans. Not only does this save ya $5 a fan but it also eliminates that annoying low speed PWM hum .. in other words, all the advantages of PWM and none of the disadvantages.

If using PWM fans, ya would be better off with the Swiftech splitter.

http://www.frozencpu.com/products/20988/ele-1196/Swifte...







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a c 519 V Motherboard
September 11, 2014 7:00:50 PM

Stardust342 said:
clutchc said:


Then that's why it isn't working. The fans will run at full RPM all the time. There is no PWM control w/o the PWM wire and no tach feedback w/o the other wire.

Are you sure it doesn't have the pwm wire? I do get a rpm reading in bios and aida64...


OK. After looking closer at the pic you posted, I see that the two wires are indeed the tach and the PWM. The missing wires are the +12V and the neg. Those are coming from the Molex. I was looking at the header backwards. My bad.

If the splitter is wired correctly otherwise, it should work.
You said you tried the header with a single fan and it worked. have you tried the splitter with just a single fan to see if it works?
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September 11, 2014 7:28:06 PM

clutchc said:
You said you tried the header with a single fan and it worked. have you tried the splitter with just a single fan to see if it works?


Yes, I have. 2 different fans too. Didn't work of course.
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a c 519 V Motherboard
September 11, 2014 7:30:27 PM

Stardust342 said:
clutchc said:
You said you tried the header with a single fan and it worked. have you tried the splitter with just a single fan to see if it works?


Yes, I have. 2 different fans too. Didn't work of course.


At this point I would return the splitter. If it doesn't work with a single 4 wire PWM fan, it must be mis-wired.
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September 11, 2014 7:32:59 PM

clutchc said:
Stardust342 said:
clutchc said:
You said you tried the header with a single fan and it worked. have you tried the splitter with just a single fan to see if it works?


Yes, I have. 2 different fans too. Didn't work of course.


At this point I would return the splitter. If it doesn't work with a single 4 wire PWM fan, it must be mis-wired.

I just don't understand how that could be... I got two and they both don't work so I have no idea why they don't work. I have a z87i-Deuluxe I may try them on, but if that doesn't work I'll see if it is possible to return them.
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a c 519 V Motherboard
September 11, 2014 7:44:20 PM

It may be a motherboard thing. If the BIOS doesn't see a load on the +12V and neg pins, it may not activate the PWM controller. That's why it works with the PWM fan plugged directly into the header itself, but not when those 2 pins are not populated.

For a test, you could rig up a 2 wire fan to the empty pins on the 4 wire header and see if that brings the controller to life.
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September 11, 2014 7:49:54 PM

clutchc said:
It may be a motherboard thing. If the BIOS doesn't see a load on the +12V and neg pins, it may not activate the PWM controller. That's why it works with the PWM fan plugged directly into the header itself, but not when those 2 pins are not populated.

For a test, you could rig up a 2 wire fan to the empty pins on the 4 wire header and see if that brings the controller to life.


I have a fan from a psu that has only 2 wires, so if I put those bare wires through the fan splitter's empty connectors to the motherboard will that work? Also they aren't labeled on the psu fan, one wire is red and the other is black...
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a c 519 V Motherboard
September 11, 2014 7:53:37 PM

Stardust342 said:
clutchc said:
It may be a motherboard thing. If the BIOS doesn't see a load on the +12V and neg pins, it may not activate the PWM controller. That's why it works with the PWM fan plugged directly into the header itself, but not when those 2 pins are not populated.

For a test, you could rig up a 2 wire fan to the empty pins on the 4 wire header and see if that brings the controller to life.


I have a fan from a psu that has only 2 wires, so if I put those bare wires through the fan splitter's empty connectors to the motherboard will that work? Also they aren't labeled on the psu fan, one wire is red and the other is black...


That is something I would do, but maybe I shouldn't have suggested it w/o knowing your expertise. Black is always negative, red pos. The MB manual will tell you which pin on the 4 pin header is + and -
Do the test at your own risk.

Or better yet, get a different arrangement.
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September 11, 2014 7:56:53 PM

clutchc said:
That is something I would do, but maybe I shouldn't have suggested it w/o knowing your expertise. Black is always negative, red pos. The MB manual will tell you which pin on the 4 pin header is + and -
Do the test at your own risk.

Or better yet, get a different arrangement.


Well this is the only option, because I would have to chop the fan splitter's mobo connector to get a different fan on and that would void any chance of return...
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September 13, 2014 10:48:36 AM

Ok, I tried the fan splitter on my z87i-deluxe motherboard, and no cigar. If I have to somehow attach a fan to the empty pins to trigger the PWM controller, no way I'm going to do that. Are you sure that swiftech one will work, JackNaylorPE?
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a c 243 V Motherboard
September 13, 2014 11:10:12 AM

It's worked on other builds but note that Corsair PWM fans are known to be problematic. I couldn't find Darlene's original post but did find it quoted. I have seen various psts on OC saying that you can get splitters to control 4 or 5 Corsair SP's but greater than that and they go to full speed. This is unique tot he Corsaie fans, no other fan that I have heard of behaves in this manner.

http://www.overclock.net/t/1506812/the-best-pwm-rad-fan...

Quote:


So that it helps everyone;

The issue with daisy chaining a lot of PWM fans onto a single PWM header varies from one fan model to another, and one mobo to another.

What happens is that as more and more fans are added, the portion of the PWM pulse that's supposed to be low, theoretically 0V, it starts rising above the 0V level by anywhere from a few millivolts to several tenths of a volt.

The more it rises above 0v, once it gets to a few tenths, then the fan doesn't effectively see that as being off time, and so if you had a pulse that was fully on for 20% of the time, but didn't go close enough to 0V for the other 80% of the time, then the fan would see it as a pulse much wider than 20% and not be able to slow down to where it should be at 20%.

The Corsair PWM fans are the very worst in this respect . . . .

Once you have more than about 5 or 6, depending on the mobo, you progressively loose the ability to run them at lower speeds.

Once you add a few more, and they all run at max, regardless of where you set the PWM percentage.


Running 6 or eight PWM fans, any PWM fan but Corsair that is, for a rad setup, from a single header should never cause a problem . . . .

But once you get to where you're talking about 12, or way more, then the "Corsair Syndrome" has to be watched out for.

Keep in mind also that while the CPU and CPU Opt headers are both PWM, they are not necessarily separately driven, so that splitting the number of fans across both of them, is not electrically different than having them all on either one. . . . . Though that too may well vary by mobo


Those Swiftech splitters work fine. I've not seen any issues inherent in them.

Guys who complained about them failed to understand that it wasn't a splitter issue, but that they just make it easy to daisy chain enough fans so that the actual number of fan PWM connections becomes the issue when the controller can't handle them all.


Darlene


The issue is that Corsair does not follow the Intel PWM standard with their fans, since they designed them primarily to work with their own Corsair Link system. . .


Too bad you already bought the fans as the cost savings on the 3 pin fans ($35) would have more than paid for the PCB costs.
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September 13, 2014 11:20:35 AM

Well I'll get it and try it. Right now I have 5 fans hooked up directly to my mobo just so I can use my computer. And yes, I can control the pwm of all of the ones I have plugged in right now.
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a c 243 V Motherboard
September 13, 2014 11:54:00 AM

It seems as ya add fans, it increasingly loses you the low end .... I run 15 fans off 3 Phanteks ones

5 case fans on CHA_1 header

4 rad fans (280) on CHA_2

6 rad Fans (420) on CHA_3

Asus Z97 boards are all PWM now so with 6 PWM headers, you can run a lot of fans
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September 25, 2014 2:41:23 PM

I finally bought the swiftech pwm fan controller, and just got it a few minutes ago. I hooked it up to sata power, connected the pwm connector to the motherboard. I attached a pwm fan to the controller, aaaaaaaaand..... it ran 100% speed. >.<
So unless there is a magical solution, I am going to have to get a dc fan controller :|
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a c 243 V Motherboard
September 25, 2014 3:24:42 PM

What is it connected to on the other end ?

Try it with just one fan and no SATA power.
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September 25, 2014 3:45:20 PM

It goes motherboard to swiftech pwm fan controller to 8x fans. I am using an SP120 as previously mentioned.
Without the sata power it does nothing... because the connector to the motherboard only has the rpm and pwm pins.
If I connect sata it runs 100% always. Is this because of corsair fans or because my motherboard?
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September 25, 2014 3:52:41 PM

I GOT IT!
I needed to connect it to either a CPU or CPU_OPT connector!
It was probably obvious that I needed to do this, but I just didn't realize it couldn't be a case fan connector.
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a c 243 V Motherboard
September 25, 2014 3:54:58 PM

Yes but what header on the MoBo ?

If you connect it to a header that is DC Voltage, it is sending a voltage signal not a PWM signal ..... 12 volts will be full speed, 7 volts lower and 5 volts near lowest. Now of you go and connect a 12v power cable from the PSU (the sata cable), it will see 12v and push all ya fans to full speed.

That's why I asked you to connect just one fan.

1. If one fan runs under speed control with SATA cable connected, we know that it's a PWM Header.
2. If one fan runs under speed control without SATA cable connected, and then goes full speed with it connected, we know that it's a DC header.
3. If we are same as condition 1 but as we add fans, we start losing low speed capability, we know its the infamous "Corsair PWM is not real PWM" problem.

Unless they have changed the design, No way PWM will work on 8 Corsair fans.....See my quote of Darelene's post above.


Stardust342 said:
I GOT IT!
I needed to connect it to either a CPU or CPU_OPT connector!
It was probably obvious that I needed to do this, but I just didn't realize it couldn't be a case fan connector.


Of course, see above.... PWM only works on PWM headers...and on Z87, the only one ya got are CPU and CPU_OPT

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September 25, 2014 4:04:02 PM

I had pwm working on case connectors as well, but it didn't read the rpm on speedfan, but I could control the speed.
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