Is there a molex to PWM with working PWM?

Originally Posted by ssateneth

Otherwise, I'm looking for a device that takes in 12v power from a 4 pin molex, can split it to 8 4-pin PWM fans, and regulateall the fans' speeds with some sort of PWM signal generator that does not come directly from the computer. Does such a thing exist?

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Originally Posted by ssateneth

I have 8 fans on my radiator that is powered by a single molex. The placement of the radiator makes it impractical to run 8 individual PWM lines to my PC (its about 10 feet away). Most good fans these days are PWM operated. I'm not sure if it's 'allowed' to lower input voltage to a PWM fan (damage?). If it is, then we can pretty much stop right there. Otherwise, I'm looking for a device that takes in 12v power from a 4 pin molex, can split it to 8 4-pin PWM fans, and regulateall the fans' speeds with some sort of PWM signal generator that does not come directly from the computer. Does such a thing exist?

If you need some context, I have an external radiator/fan/pump/reservoir tower setup that uses a single long 4 pin molex to power all the fans and pump. I split the molex once at the tower to give 12v to the pump, then another splitter on the other output that's spliced to give 5v on one plug and 7v on the other plug (so I can run the fans on 5v or 7v, or not use the extra splitter and get the full 12v). The fans' bearings are pretty loud (the bearings make audible noise, even overpowering airflow sound @ 5 volts), so I want to upgrade the fans to something with a quieter bearing. Most quiet bearing fans are PWM these days, and I don't want to damage the fans by giving them a power other than 12v. There would be 8 fans total on it so adjusting PWM on all the fans at once would be good if I had an adapter for PWM signal and could generate it locally instead of all the way from the PC.

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Originally Posted by ssateneth

Noctua one seems just about what I need. Now just have to split it 8 ways! Actually ebay brought up something called SilverStone Technology CPF04 which takes SATA power and a PWM signal input and spits out 8 4-pin PWM fan connectors (ninja-edit: its not much different that the made-in-china bare PCB that I linked earlier). The aura computer one seems over-engineered for what I need. An all-in-one package would be ideal but that would mean something created from scratch and I'm stupid when it comes to that (I dont even follow the DIY link, its all latin to me)

Anywho, thanks for the links/help. Might make a purchase soon

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Originally Posted by ssateneth

Hmm, the phobya one has the advantage of not needing an extra power connector, so I could just go Power -> noctua PWM generator -> phobya splitter -> fans. Great options. If the noctua PWM generator acts as a passthrough for power, then it shouldnt be strenuous on the device and I won't feel bad for adding 8 fans on it.

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Originally Posted by ssateneth

I had always thought that the PWM signal was sent to the fan, then the fan circuitry itself decided to open or close the 12v power depending if PWM is high or low, which wouldn't put any strain on the PWM sending device itself. Thats why some adapters only need PWM and RPM signal sent to/from motherboard while 12v + ground can be sent elsewhere as it doesn't need any extra circuitry, which made me think that the noctua PWM device simply created a local PWM signal and just let 12v + ground pass through without any processing (hence no extra strain).

I guess it can be tested with a multimeter, but im 98% sure that there is no significant load on the PWM line and it's simply an oscillating binary signal.

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Originally Posted by ssateneth

I'm not too worried about any current strain anyways. WIth 8 fans going full bore (BGears Blasters, 1800RPM 140mm), power at the wall only goes up 20 watts. Thats less than 2 amps @ 12v. Any other fans that I've been looking at are a little slower and pretty much guaranteed to use less power.

Anywho,the input on this thread has given me some great information, thanks for the help.

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The Noctua PR guy also tells me they have tested the FC1 with 100 fans! Now, granted, these were Noctua fans which don't draw much current, but you get the idea that the FC1 will control all the PWM fans that will fit in your case.

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Originally Posted by doyll

Quote:

Originally Posted by Faster_is_better

Hmm, this Noctua accessory could be useful for me some day if I transition from GPU PWM signal to something else. I may have to buy just to test, and it could be nice to use for my pump to quiet that beast down lol.

According to this overclockers review (source)
I need a PWM signal generator for 12 fans (maybe 16 some day), so this could be nice. I'm already pulling power straight from PSU, (Delta fans) and there haven't been a lot of options for controlling over 8 fans via PWM, at least with the same PWM source.

I definitely wouldn't trust it for to much of a 12v load though. Their documentation lists 3 of their Industrial PPC3000 fans as example to control, and those only draw .3A each, so less than 1A total for their 3 way splitter. Didn't see any official max rating in their documentation though.

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I really have to wonder what was lost in translation from what Noctua actually said and reviewer's 'tested the FC1 with 100 fans' .. 10 fans rated 0.1amp yes .. but I'm not believing 100 fans regardless of how low the power rating is.
Same goes for PWM signal support .. I'll believe PWM signal can control 10 PWM fans, but not 100 fans.

NF-A14 iPPC-3000rpm is rated 0.55amp / 6.6watt; 12v, .. at least that's what Noctua website says.

http://noctua.at/en/nf-a14-industrialppc-3000-pwm/specification

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Originally Posted by axipher

I agree with the first bolded point that I doubt a single fan controller channel would handle 100 fans, that is a ton of start-up current and lost of motor inductance to deal with.

For most high quality fans, the PWM signal should be able to control 100 fans as long as they aren't super long runs tiny thin wires. Most PWM circuits I've seen use the 12V rail, but I believe the actual PWM circuit on the fan itself normally only needs to see a minimum of 3.3V. So with 100 fans, even if that 12V PWM signal drops down to 8V, as long as the square wave itself is still clean and is pulsing on and off consistently, all the fans should run fine.

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Originally Posted by doyll

Quote:

Originally Posted by axipher

I agree with the first bolded point that I doubt a single fan controller channel would handle 100 fans, that is a ton of start-up current and lost of motor inductance to deal with.

For most high quality fans, the PWM signal should be able to control 100 fans as long as they aren't super long runs tiny thin wires. Most PWM circuits I've seen use the 12V rail, but I believe the actual PWM circuit on the fan itself normally only needs to see a minimum of 3.3V. So with 100 fans, even if that 12V PWM signal drops down to 8V, as long as the square wave itself is still clean and is pulsing on and off consistently, all the fans should run fine.

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My saying 10 fans on a single PWM signal source is based on using PWM controlled computer fans on many different motherboards and finding 8-12 fans to be the maximum number that can be controlled. This is backed up by no PWM splitter hubs having more than 8x fan headers.

No idea where you come up with this 12v stuff, but there are no 12v used in computer PWM control signals.

Here is excerpt of relevant data for PWM as we use it in our computers from "4-Wire Pulse Width Modulation (PWM) Controlled Fans" updated in 2005


From below source
www.formfactors.org/developer/specs/4_wire_pwm_spec.pdf

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