Are 3 pin Fan Y Splitters ever a problem?

johnbentley · Post by **johnbentley** » Wed Oct 28, 2009 10:46 pm

Do 3 pin Fan Y splitters, where one 3-pin motherboard header drives two fans, work straightforwardly?

If the motherboard header is controllable via speedfan will it vary 2 fans attached, vai the Y splitter, in the same manner as if 1 fan is attached, without the Y splitter?

ntavlas · Post by **ntavlas** » Thu Oct 29, 2009 1:22 am

The 2 fans will get regulated just as a single fan would. There are a couple of issues to keep in mind though. The combined power draw of the 2 fans should be kept low. Using two 0.1 amp fans should be safe although some fans draw less power than their rating would suggest. For example, 1000rpm nexus are rated @ 0.3 amps, in practice they draw less then 0.1. Xbit labs has measured the actual power draw of various models in their recent fan roundup.

The other issue is that some y splitters are poorly made and as a result electrical contact can be poor, making the fans stop. I don`t know whether it`s a common problem or not, but it has happened to me.

nomoon · Post by **nomoon** » Thu Oct 29, 2009 8:41 am

They've never been a problem for me. Low speed fans tend to be well below the maximum threshold of the motherboard, even when two or three fans are used. I'd suggest that you check the amp rating on the motherboard and the fans as a precaution, though the previous poster's comment suggest that you'll probably be okay even if the ratings are marginal.

johnbentley · Post by **johnbentley** » Fri Oct 30, 2009 7:13 am

The X bit labs fan power draw (and other results) shows that some of the fans I'm interested will draw more than 0.1 amps. The motherboard I'm eyeing off doesn't provide its fan header power rating in the specs. This route, then, is all a bit too tricky for my tastes. Your responses have saved me frustration, thanks

In my system (I'm sourcing gear to build for family) I use mcubed Tbalancer which allows me to software control fans connected to the controller. This also reads speedfan values. It works but, in the end, I find the Tbalancer software a bit clunky and the whole solution a little bit cumbersome (and expensive).

So I'm looking for a simpler solution to software controllable fan control. Given that most motherboards only have one or two (of four or five) fan headers that are controllable it seems reasonable to give up on individual control of fans and allow a fist of them to simultaneously ramp up when necessary.

I wonder if the Akasa PWM splitter - smart fan cable (3 x 4 pins from a single 4 pin) with a molex power input could be used with voltage (3 - pin) fans (if the motherboard can be configured to send a voltage signal through its 4 pin headers)? Is there is an analogous product with 3 pin connectors? Would either by available in Australia?

ntavlas · Post by **ntavlas** » Fri Oct 30, 2009 8:20 am

Which fans do you have in mind? I think my 2x0.1amp guess is a little too conservative, a header should be able to provide more than 2,5 watts, around 4-5 watts is more likely.

The pwm splitter is also a good idea if you can find the skythe kama pwm fans. To control 3pin fans with this splitter you will need a pwm to analog converter like the nanoxia discussed in this thread. Arctic cooling pwm fans also have a built in splitter. A bit clicky at low speeds but watch out for their new models.

Another alternative is the skythe kaze server, a 4 channel controller with temp based control. The poor man`s t-balancer if you like.

johnbentley · Post by **johnbentley** » Wed Nov 04, 2009 8:02 am

ntavlas, thanks. You have many good suggestions to consider.

The fans I have in mind for the system I'm to build, for an Antec Solo:
* Case, front. Nexus Real Silent Case Fan DF1209SL-3, 92mm Sleeve bearing.
* Case, vertical (Rear). Scythe Slip Stream SY1225SL12M, 120mm rated 1200 rpm, Sleeve bearing.
* CPU cooler Scythe. S-Flex SFF21E, 120mm rated 1200 rpm Fluid Dynamic Bearing.
* Graphics card cooler Scythe. S-Flex SFF21E, 120mm rated 1200 rpm Fluid Dynamic Bearing.

So I note that if the revision of your guess of motheboard header power output reflects the reality of my chosen motherboard these fans might be ok for 2 split onto 1 header.

Thanks to your post I am considering the Skythe Kama pwm. They are sleeve bearing so I'd be worried about using them in High Heat or Horizontal positions.

But from Fan Roundup #5: Attack of the 120 Scythes

mikec wrote:Some will want to argue that the sleeve bearings of these Scythe fans don't hold up well under high heat conditions. It's not as cut and dry as some folks would like you to think;

I neglected to write that I do have the Nanoxia PWM converter (in my current system). It works like a charm between by 4 pin PWM only header and my 3 pin fan. Speedfan theferfore controls the fan. I bought this before the Tbalancer if you are wondering why I have both.

The skythe kaze server, or something like it, may well be a good solution. Although I have always been sceptical that third party sensors, installed by me, are not going to be as accurate as those installed by the motherboard manufacturer. Is this a mere prejucide against third party sensors?

I have created a new post Motherboards with lots of fan headers Speedfan controllable in the vain hope that all these issue will be made superfluous via a good motherboard.

ame · Post by **ame** » Wed Nov 04, 2009 12:04 pm

I have a very similar fan arrangement.

I was running 3 fans in my Solo off the same header. 2*92 Nexus and one 1200 RPM Slipstream. I had it running like this for about 6 months with no problems.

Finally about 2 weeks ago, I wanted the Nexus 92s to run slower. So I now run them @ 5V using 'SPCR 5V trick'. So they are now connected directly to the PSU, and I'm using the MOBO fan header just for the Slipstream.

Im using an Asus MOBO that has only PWM control for CPU fan (voltage is 12V). I'm using ArcticCooling PWM fan ~500 RPM idle to ~650 RPM load.

The laudest fan in this system is the Slipstream 1200 that is running about 850-950 RPM (60% in the BIOS)

EDIT: BTW AC fans are (also) hydrodynamic bearing.

RogueTrader · Post by **RogueTrader** » Sat Jan 16, 2010 10:01 am

I have a demo xbox like the ones you find in gaming stores. So basically an entire set including furniture, xbox and television. It's the old one, not the 360. The fans make a very annoying and loud sound.

I want to replace the 70mm xbox fan with a 80mm Scythe fan. I know this will work because I can find a lot of tutorials about it on the internet. But... the furniture itself is also cooled with a 100mm fan. I want to replace it with a Scythe fan. The original one in the furniture isn't 12v. So I want to power the 12v Scythe from the xbox with a splitter.

The xbox fan only has 6 volts. Is it possible to use a 3-pin splitter and an extension cable for this?

trxman · Post by **trxman** » Wed Jan 27, 2010 11:43 am

I have Asus P5Q Premium with 5 fan headers, but I can control only 3 of them.

I want to connect more (2 or 3) fans to every of these 3 controlable headers.

fans are Noctuas ranging from 1.1 to 1.44W (factory specification).
xbit labs state it's more probable about 1.0 to 1.1W each.

so, is there some general rule of the thumb about the power that should not be exceeded per fan header?

RogueTrader · Post by **RogueTrader** » Wed May 12, 2010 10:31 am

RogueTrader wrote:I have a demo xbox like the ones you find in gaming stores. So basically an entire set including furniture, xbox and television. It's the old one, not the 360. The fans make a very annoying and loud sound.

I want to replace the 70mm xbox fan with a 80mm Scythe fan. I know this will work because I can find a lot of tutorials about it on the internet. But... the furniture itself is also cooled with a 100mm fan. I want to replace it with a Scythe fan. The original one in the furniture isn't 12v. So I want to power the 12v Scythe from the xbox with a splitter.

The xbox fan only has 6 volts. Is it possible to use a 3-pin splitter and an extension cable for this?

I'm about to order some hardware and am going to order some fans for the xbox.

So, is it possible to power two fans using 1 motherboard fan header? And if the fans are designed for 12V, but only get 6V, will the start spinning? I believe they will spin at half the speed? And is there any danger of frying the motherboard fan header using a splitter and two 12V fans?

ascl · Post by **ascl** » Wed May 12, 2010 2:55 pm

Yes, there is a danger. It depends on how much power the fans draw, and how much the motherboard can handle. On my gigabyte mobo (and I believe most new GB boards), the fan headers can handle up to 1a.... so if you are hanging efficient fans off it, you could easily drive 3 or 4 fans. OTOH if you are powering a SanAce monster, it can't even handle one!

One thing to be aware of, is that fans typically have a greater start-up draw than once they are running.

The startup voltage of a fan is entirely dependent on the fan itself. Some fans will start at 4 or 5v, some not until much higher.

RogueTrader · Post by **RogueTrader** » Wed May 12, 2010 9:25 pm

Standard xbox 70mm
=>
Scythe S-Flex SFF80C 80mm 2,000 rpm Version:
28.7 CFM = 49 mÂ³/h / 20.0 dBA | DC 12 V | 0.12 A

Second fan
=>
Scythe KAZE-JYU SY1025SLN12H 100mm 2000rpm Version:
58,00CFM = 98 mÂ³/h / 30,68dBA | DC 12 V | 0.16 A

I've seen tutorials about 12V fan mods for the XBOX using the power cable from the harddrive. Maybe it is better to use that for one of the fans.

ascl · Post by **ascl** » Wed May 12, 2010 9:46 pm

Googling shows this:

http://www.silentpcreview.com/article695-page5.html this is for the 120mm fan, so I have no idea if its the same. But, assuming it is, starting voltage is 8.9v. If you dig around on the scythe website you might be able to find your exact fan.... or, if you have a fan controller, you could just try it.

http://www.scythe-eu.com/forum/other-fa ... e-jyu.html
That might be the exact version? Anyway, starting voltage 4-5v.

EDIT: FWIW I would guess (and its purely a guess) that running these two fans from a CPU header would be okay.

BlackWhizz · Post by **BlackWhizz** » Thu May 13, 2010 2:44 pm

If you can get it a Mcubed FanAMP is a good thing for you. Its like a amplifier for your fans to hook up more fans to a single fan header. Because the amp draws its power from the power supply is thing can run to 50w or 25 of power (dont knwo that exactly).

LEO454 · Post by **LEO454** » Thu May 13, 2010 11:47 pm

Postulating from the electronic components available for manufacturers to use, the smallest voltage regulators are 200 milliamp to 500 milliamp which cost on average $ 0.69 while a larger 1.5 amp version retails $1.89 so at the very least you can assume a safe range of .2 to .5 amp range without burning components. Heat would be the problem if you exceed the fan header current capability.