PWM Daisy Fan Question

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May 28, 2014
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Your motherboard header sends thousands of "pulses" for each revolution of the fan, hence "pulse width modulation." The fans change speed based on the voltage going through the circuit. The fan hub you're looking at doesn't appear to have any PWM function. If it does, however, it will change the speed of all the fans linearly with no loss.

EDIT: Never-mind, it does say PWM. I didn't see that at first. So the hub reads the pulse from the MOBO PWM header and uses a capacitor to achieve adequate and equal voltages across all the fans relative to the input.
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Your motherboard header sends thousands of "pulses" for each revolution of the fan, hence "pulse width modulation." The fans change speed based on the voltage going through the circuit. The fan hub you're looking at doesn't appear to have any PWM function. If it does, however, it will change the speed of all the fans linearly with no loss.

EDIT: Never-mind, it does say PWM. I didn't see that at first. So the hub reads the pulse from the MOBO PWM header and uses a capacitor to achieve adequate and equal voltages across all the fans relative to the input.
 
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Solution
I can't speak to the Silverstone hub or the AC fans.... this is the only PWM hub I have ever used

http://www.swiftech.com/8-WayPWMsplitter.aspx

Daisy chain is a wiring thing, not software or even hardware.
I assume the daisy chain wire simply has 4 wires going to the 1st fan and 3 going to all the others.

The daisy chaining thing is really not daisy-chaining, in the true sense, as you can't actually wire PWM in serial. You do run the risk of blowing your CPU header if you power 5 fans off your MoBo Header. The hub makes infinitely more sense as the power for the fans comes in.

There are 3 types of fan hubs available ....

PWM (i.e. Swiftech) - This takes a PWM signal and controls a number of PWM fans. May be used without a power cable of total fan wattage does not exceed MoBo header rating (typically 1 amp). Problematic with Corsai PWM fans and also may exacerbate the low speed PWM hum / ticking found on some PWM fans. Advantage of PWM is that constant 12v power allows fans to go at a lower % of full speed.

DCV (i.e. ModMyToys) - This takes a DC voltage signal and controls a number of DCV fans. Can only be used without a power cable where total fan wattage does not exceed MoBo header rating (typically 1 amp). Using a power cable sends all fans to full speed as 12v signal overcomes MoBo signal. No issues with low speed PWM hum / ticking found associated with PWM fans. Generally, DCV fans don't have the ability to go to the same low rpms as PWM fans but DCV are substantially cheaper

PWM (or DCV) => DCV (i.e. Phanteks) - These take a PWM signal and convert it to DCV for a "best of both worlds" scenario. Controls less expensive DCV fans with the same range at low rpms as PWM fans but w/o the low speed hum / ticking associated with some PWM fans. As with PWM hubs, power cable need only be used when total fan wattage exceeds header rating. Can also be used on DCV headers but agan, if power cable is used, the 12V power will over ride the variable speed DV voltage coming from the MoBo header.


 
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That is not how PWM works .... and the capacitors job is not to control speed put to filter the input voltage from the PSU and provide a constant and stable "clean" 12 volts.

Hubs like the Phanteks take the PWM signal and sent out by the header and send out an equal voltage across the fans, raising the voltage to increase speed and decreasing the voltage to reduce speed.

The signal sent on true PWM hubs is always 12 volts. The way PWM works is not by sending out varying voltages but but varying the time interval between power being applied. To increase speed...

DCV = 5.5v.....5.5v.....5.5v.....5.5v.....7.0v....7.0v.....7.0v.....7.0v..... more voltage means more speed, less voltage means less speed

PWM = 12v Power On....Power OFF xxms....12v Power On.... .Power OFF xxms ..... the shorter the Power OFF duration, the faster the fan speed, the longer the Power OFF duration, the slower the fan speed

 
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You just quoted me and said what I said in lamen terms. In order to power multiple fans from the same header you need a capacitor, which you might not understand fully.
 
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PWM does not work by "change speed based on the voltage going through the circuit". PWM changes speed by varying the time of POWER OFF Intervals between POWER ON intervals, the voltage never changes.

I ran an electric power utility for a half dozen years, and have been designing plants for 30 years. I know how capacitors work and what they are for. They function to smooth out variations in power output..... here as stated on the web site ... it takes in "dirty" 12v power and outputs clean 12v power....which has no possible effect on fan speed. It is not relative to anything related to speed control.

Here's the "daisy chaining" cable the OP referred to with regard to the daisy chain feature. It has no capacitor.

http://www.arctic.ac/us_en/pst-cable.html

Clearly, the cable is controlling 4 fans and has no capacitor....it instead relies on the VRM of the MoBo / PSU to provide clean 12v power to the fans. The hub on the other hand does the exact same thing.... it takes the dirty input power from the PSU and uses a capacitor on the INPUT side to clean that power up

The Silverstone web site states this very clearly

http://www.silverstonetek.com/product.php?pid=526

Powered directly by SATA cable from the computer power supply and filtered through a built-in 2200μF capacitor, the CPF04 can provide clean, stable voltage to any fan for optimal performance.
Click to expand...

Take this capacitor out and, theoretically, at best all it means is that the 12v power might be somewhat "dirtier" than it would otherwise be . I say "might" cause PSUs do a pretty good job of cleaning up the power. Look at the test results on jonnyguru to see just how good a job they do. And our HD's, fans, SSDs and everything else connected to our PSUs seems to survive just fine without additional capacitors.

Why did Silverstone include this if it wasn't necessary ? Perhaps to differentiate themselves from ModMyToys and Swiftech and every cable splitter manufacturer, none of which seem to need this capacitor but which work perfectly fine.

Silverstone hub w/ capacitor .... nice feature, I guess, doesn't cost more than a few cents, but redundant w/ dent VRM on MoBo / PSU
cpf04-05.jpg


So... no a capacitor is not required to control multiple fans:

1. The Daisy Chain cable above doesn't have one ... it works fine
PST_Cable_T01.png


2. The Swiftech PWM hub doesn't have one and it's the defacto standard
8WAY-PWM-SPLITTERX600.jpg


3. The ModMyToys PWM hub doesn't have one .... it works fine.
ele-1299.jpg


 
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I'm sorry but I just can't take you seriously. I don't know if there's a language barrier or what but you're literally contradicting yourself and agreeing with me at the same time.

Also, the OP ordered the Silverstone hub in question and NOT the daisy chain cable. Why are you even mentioning other products that are irrelevant?
 
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You stated and are still trying to defend an unfactual statement:

In order to power multiple fans from the same header you need a capacitor, which you might not understand fully.
Click to expand...

Well if that is true as you claim, instead of repeated vague insinuations as to what other people know or do not know .... why not just explain as to how the Swiftech, Artic and ModmyToys Splitters have managed to remain on the market satisfying customer after customer year after year if none of them have the capacitor that you say is absolutely required. There are dozens of products on the market that do this successfully and don't have these capacitors. If you know what you insist we don't know, please explain how all these products work if they don't have this capacitor.

45 here
http://www.frozencpu.com/cat/l3/g47/c251/s1325/list/p1/Fan_Accessories-Fan_Cables-PWM_Cabling-Page1.html

39 here
http://www.frozencpu.com/cat/l3/g47/c121/s424/list/p1/Fan_Accessories-Fan_Accessories-Multi_Fan_Ports-Page1.html

84 products on one site that control multiple fans and not one that has this capacitor that you insist is required to control multiple fans. How can that be ? How do they sell this things ? Why have they all not been shut down for making fraudulent claims if they can't possible control multiple fans w/o this capacitor ?

 
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Let's play a game. What I said vs. what you said. I hope this clears things up for you.

Me:
Your motherboard header sends thousands of "pulses" for each revolution of the fan, hence "pulse width modulation."
Click to expand...

You:
PWM changes speed by varying the time of POWER OFF Intervals between POWER ON intervals, the voltage never changes.
Click to expand...

BTW: The voltage does change. Powering off means 0 voltage, and turning on is a change in voltage.

Me:
The fans change speed based on the voltage going through the circuit.
Click to expand...

You:
DCV = 5.5v.....5.5v.....5.5v.....5.5v.....7.0v....7.0v.....7.0v.....7.0v..... more voltage means more speed, less voltage means less speed
Click to expand...

Me:
. So the hub reads the pulse from the MOBO PWM header and uses a capacitor to achieve adequate and equal voltages across all the fans relative to the input.
Click to expand...

Silverstone (via you):
Powered directly by SATA cable from the computer power supply and filtered through a built-in 2200μF capacitor, the CPF04 can provide clean, stable voltage to any fan for optimal performance.
Click to expand...

Also please note that capacitors come in all shapes and sizes and just because you're using one somewhere else doesn't mean you're not using one at all. I prefer to do things proper.

 
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