Noctua PWM Fans

[Endlin3]

I want to get a 480 radiator with 4 x Noctua NF-F12s (or maybe 8 in push/pull) but I want them to be controlled via the PWM mobo header so when the system is idle they're not blasting at full speed.

What is the best way to connect upto 8 NF-F12s to the PWM header without overloading it?

 

[Diggrr]

With the splitters I've seen for PWM, you can get 4 of them together per header. I bought one made by Gelid Solutions (via frozencpu.com) that uses a single power supply molex to run the fans, but RPM wires from one fan are wired back to the motherboard header. The PWM's are all hooked together, so the outgoing signal from the header gets to all four fans.
Sounds complicated, but the cable makes it gravy to hook 'em up.

You'll need two PWM headers for 8 fans though (using this type of cable), you can't link two of these together to one header because the RPM signal coming from two fans (one per pigtail set) into one header will annoy the motherboard greatly.
Since the fans are actually powered directly off of the power supply, there's no danger of overload and you can run any size fans you'd like.

to the forums!

 

[Diggrr]

BTW, Noctua's don't blast...they gently whisper!
I run 3 myself, though I run the NF-S (silent) models.

There's a pic. 4 tails for fans on one end, a power plug, and a header plug so PWM & RPM are handled by the motherboard header.

View attachment 108707

 

[Endlin3]

Sweet,
well I can't find that particular cable on frozencpu, only this:
http://www.frozencpu.com/products/13315/cab-455/Gelid_Solutions_PWM_Y_Splitter_Cable_CA-PWM-01.html
but that's not it.

any idea what that particular cable is called, although I doubt you still have the packaging.

Also, the NF-F12s come with a splitter themselves, so could you use that cable of yours and the splitters to get 8 or even more onto one PWM header?

 

[Endlin3]

Oh found it on Amazon. is just called 1-4 Splitter PWM cable

 

[Diggrr]

Yep, 1-4 splitter. I do have the packaging. It arrived last week, and I'm waiting for my video card RMA to start building the case and other goodies.

You can get 7 fans that way...one of the fan plugs on the splitter cable reports RPM back to the motherboard header (yellow wire is hooked up only on one plug). You cannot mix two fans together on that one wire or your motherboard will have an impossible time of regulating speeds.
See, a fan sends two "blips" per revolution to the motherboard via the yellow wire, that's how the motherboard knows how fast the fan is moving.
If you hook two fans to that connector that's sending that signal, the motherboard gets 4 blips per two fan's single RPM, and two fans are usually slightly out of sync, so it gets confused as to the real RPM and can't give a good power modulation signal back to the fans. The fans start revving up and down, and sometimes will even stop randomly.
Don't go there. You won't like it.
The one plug that uses the yellow wire MUST be a single fan for the whole thing to regulate correctly.

Sorry!

 

[Diggrr]

Eh nevermind. I'm sure now that it wouldn't work well.

 

[ehume]

What you want to do is to power your fans from the PSU via Molex, and control your fans with the PWM signal from the motherboard. You want one of these. I have one, and it does what you want.

Check out this review, at the bottom.

 

[Endlin3]

Ok, well I've already gone n bought the Gelid 1-4 splitter.

If I plugged in a Noctua 2 way splitter into the end of those 4 female connectors on the 1-4 Gelid splitter, would that work and give me 8 fans running off that Gelid cable?

 

[illli]

those splitters look pretty cool. i didnt know they existed until now

 

[Endlin3]

Ok, I'm a little disappointed, I hooked my Noctua NF-F12 up to straight 12v power and it's not as whisper quiet as everyone makes out.
it's louder than an Arctic Cooling F12 i had lying around, which spins at 1350rpm and according to specs I found on the net has air flow of 57 CFM
(don't know if thats true or not since they're actual site says the airflow of the f12 is 74 CFM which is probably a little bit of bull****)
but the Noctua has apparently got 55 CFM and given all the science behind this NF-F12 I was kind of expecting an inaudible fan here.
But turns out no.

So yeah, not sure about it. I haven't tested it on a rad yet and tbh given all of the raving reviews of it's performance I imagine it would tear a new one in this Arctic Cooling F12, even though it apparently has better air flow specs, but I was kind of expecting silence, and that's not what I've got here.

 

[Neuromancer]

Yep, 1-4 splitter. I do have the packaging. It arrived last week, and I'm waiting for my video card RMA to start building the case and other goodies.

You can get 7 fans that way...one of the fan plugs on the splitter cable reports RPM back to the motherboard header (yellow wire is hooked up only on one plug). You cannot mix two fans together on that one wire or your motherboard will have an impossible time of regulating speeds.
See, a fan sends two "blips" per revolution to the motherboard via the yellow wire, that's how the motherboard knows how fast the fan is moving.
If you hook two fans to that connector that's sending that signal, the motherboard gets 4 blips per two fan's single RPM, and two fans are usually slightly out of sync, so it gets confused as to the real RPM and can't give a good power modulation signal back to the fans. The fans start revving up and down, and sometimes will even stop randomly.
Don't go there. You won't like it.
The one plug that uses the yellow wire MUST be a single fan for the whole thing to regulate correctly.

Sorry!

Um what? I had a couple of beers... so the fan splitter does not work right if you use more than one fan? It should dot dot dot being a splitter send the same signal to pulse on all fans on the splitter yes?

 

[Endlin3]

Although to be fair to it, the Low Noise adapter is definitely that, attach that thing and you have silence, but you also get a drop in cooling power.

So the question is really, is an NF-F12 with a low noise adapter still better at cooling than your regular 9-10 dollar fan like the arctic cooling F12?

 

[Diggrr]

Um what? I had a couple of beers... so the fan splitter does not work right if you use more than one fan? It should dot dot dot being a splitter send the same signal to pulse on all fans on the splitter yes?

Yeah buddy, it'll send the PWM signal to all the fans, but having two fans send an RPM signal back to a single header will make it read wrong.
No two fans run the exact same RPM at a given voltage, so that RPM signal will be doubled sometimes, and sometimes out of sync, confusing the controller.

And since the PWM signal is a voltage on/off type signal, dividing into 8 fans will probably make the signal too week for the fans to use it properly.
I'm pretty sure that's why you can only find 5 fan splitters.
It's like running 4 lights off a 9-volt battery. 4 works, but 8 divides the voltage too much to light the bulbs.

**See how only one of the fan connectors has a yellow RPM wire? ALL fan splitters with RPM reporting do this.
If you double up the fans on that one plug, you'll confuse your controller and it won't be able to control fan speeds correctly. Period. That's why the cable is made that way.

View attachment 108792

 

[Diggrr]

@ Endin3,
It sounds like you only have one PWM header available.
What I would do is use one of the Gelid splitters on the PWM header for 4 fans, and use the other Gelid splitter on a regular 3 pin header.
Noctua's are rather quiet anyway, but you can use the low noise adapters on the fans plugged to the regular 3 pin mobo header if you'd like them quieter.