How should I connect the fans? Not enough headers on motherboard

Zipp · Dec 18, 2013

Hi,

I am much in doubt about how I should connect my fans in my new upcoming PC. It is most likely going to be like this: i5-4670k, Gigabyte GTX 780 Ti OC, 8 GB Corsair 1600 MHz memory, Corsair 550D case, a H100i cooler, Asus Maximus Hero and a Corsair AX860 psu.
However, the Asus motherboard only has 5 fan headers in total, and I'd like to control the H100i fans through the motherboard instead of Corsair Link (seems to cause problems for quite a few people). I was planning to connect the two radiator fans to the CPU and CPU_Opt headers, and then the pump to a chassis fan header (just to get the rpm reading - since the pump is connected directly to the psu).

But then I have only 2 headers for the 3 case fans.

So how should I connect them?

1: Could I use a y-splitter to connect two fans to one header? I couldn't find how many amperes they use though, and the motherboard states a maximum of 1A for each header - but I don't know the specs about the stock H100i fans, or the 550D case fans.

2: Get a y-splitter that connects to the PSU. But I don't know if this is necessary. Also, I already have a couple of regular y-splitters that came with some Noctua NF-F12 fans that I bought some time ago.

3: Buy a fan controller like the NZXT Mesh and control the 3 case fans manually.

4: Get another motherboard with more headers, but I have really good experience with Asus, so I think it may be a little too much to change because of the number of fan headers

What would you recommend me doing? I hope you will give me some advice, thanks

bombastinator · Dec 18, 2013

1 amp is a lot of power for a fan. I'd risk a y connector. especially for the h100i fans. you want them running at the same speed anyway.

Enrainn · Dec 18, 2013

You can use the swiftech 8 Way PWM Splitter, 8 fans for each header.
http://www.swiftech.com/8-WayPWMsplitter-sata.aspx

Zipp · Dec 18, 2013

Thanks for the suggestions

I actually just found an image of the stock H100i fans in a review (http://img.hexus.net/v2/cooling/Corsair/H100i/H100i-03b.jpg) and it shows it's 12V 0.36A fans - so that's 0.72A for two.

Do you think this is getting too close to the limit of 1A on the motherboard?

That swiftech thing looks nice - they do seem to recommend it to be used on the cpu header, but I think I'd like to keep it simple for the radiator fans (either using 1 cpu header each for them, or maybe a normal y-splitter) - and then I could use that Swifttech to connect multiple case fans to a chassis fan header. I assume that would work too since all the headers on the Maximus Hero are 4 pin?

However, maybe I am worrying too much about using a normal y-splitter?

Enrainn · Dec 18, 2013

Yes two fans with the y-splitter will work fine. And the Swiftech splitter will work on any 4-pin header, they recommend the cpu header because some motherboards only have it and some 3-pin headers.

doyll · Dec 18, 2013

Quote:

Originally Posted by Enrainn

Yes two fans with the y-splitter will work fine. And the Swiftech splitter will work on any 4-pin header, they recommend the cpu header because some motherboards only have it and some 3-pin headers.

No, Swiftech PWM splitter will not work on any 4-pin header. It only works on 4-pin headers with PWM signal on pin-4... On most motherboards the only 4-pin header that has PWM is the CPU fan header.

This applies to any PWM splitter and/or fan plugging into motherboard.. only expect CPU fan header to be PWM.

Zipp · Dec 18, 2013

I have just read that fans apparently use a much higher current when they spin up - up to twice the rated amps? So maybe I shouldn't do this for the two 0.36A fans, but only do this for lower rated case fans like the SP120 PWM Quiet edition rated at 0.08A according to Corsair?

edit:

You posted while I wrote this

Quote:

Originally Posted by doyll

No, Swiftech PWM splitter will not work on any 4-pin header. It only works on 4-pin headers with PWM signal on pin-4... On most motherboard the only 4-pin header that has PWM is the CPU fan header.

This applies to any PWM splitter and/or fan plugging into motherboard.. only expect CPU fan header to be PWM.

Does this mean it doesn't make sense to buy PWM fans for the chassis fan headers? Why do these headers even have 4 pins then?

doyll · Dec 18, 2013

You can control most PWM fans on variable voltage with no problems.

You can use a PWM splitter with molex / sata power connector plugged to PSU and 4-pin fan plug to CPU fan header. Doing this means the fans have 12v power directly from PSU and PWM signal controls that 12v power by pulsing it to control fan speed. That's what PWM is all about; Pulse-width modulation.. PWM fan has a small PCB that reads the PWM signal from motherboard to control the length and number of 12v pulses going to fan.. more and longer pulses mean fan runs faster.

Zipp · Dec 18, 2013

Quote:

Originally Posted by doyll

You can control most PWM fans on variable voltage with no problems.

You mean on the chassis fan headers or?

How do I know if the 4 pin chassis fan headers on the Maximus Hero is PWM?

There does seem to be a difference between these headers and the CPU and CPU_Opt headers in the manual - as for the cpu headers it says "PWM mode Q-Fan control", but for the chassis fan headers it says "Chassis Q-Fan control" - but it still got a min/max rpm setting, based on chassis temperature.

Would these chassis controls work with non-PWM fans?

Quote:

Originally Posted by doyll

You can control most PWM fans on variable voltage with no problems.

You can use a PWM splitter with molex / sata power connector plugged to PSU and 4-pin fan plug to CPU fan header. Doing this means the fans have 12v power directly from PSU and PWM signal controls that 12v power by pulsing it to control fan speed. That's what PWM is all about; Pulse-width modulation.. PWM fan has a small PCB that reads the PWM signal from motherboard to control the length and number of 12v pulses going to fan.. more and longer pulses mean fan runs faster.

I see, but the problem is that I'd probably want different settings for the case fans and the radiator fans - so if I used the cpu header for connecting a bunch of fans (including the radiator fans) I would have the same profile for all of them. I also think that the radiator fans are more important than the case fans, so I'd like to keep their connection simple to avoid potential issues - if that makes sense?

doyll · Dec 18, 2013

Easy way to find out if SYS fan headers are variable voltage or PWM is check the voltage on power pin.. pin-2. If it is PWM it will have 12v to it all the time. If it's voltage control the voltage will be 12 volts at full speed and lower voltage for lower speeds.

I use a PWM splitter with molex/sata power connecter and fan socket for splitter fan connector for PWM and RPM. If fan spins full speed all the time the header is not PWM.. no 12v power pulse.. only contant 12v so fan spins full speed.. If it lows down and speeds up it is PWM.. the 12v power is being pulsed to control the speed.

Chassis controls are probably variable voltage so yes, they will work with normal 3-pin fans.

If your radiator fans are moving faster why not have case fans that are supplying the air to them move faster too?? Running same number, type & speed case intake fans as radiator exhaust fans sounds logical.. It means the case intake is supplying similar amount of air into case as radiators fans are pushing out of case.

TiezZ BE · Dec 18, 2013

my asus p8p67pro has auto detect on the 4 pin chassis header, if I connect a 4 pin pwm fan it will provide pwm control. If I connect a 3 pin fan it will provide voltage control to adjust fan speed.

That Asus Maximus Hero you got is higher end than mine, I would be surpised if it didn't provide auto detect or at least a bios setting to set the control type of the 4 pin chassis header. Don't know if cpu header will do the same, never tested that with my board.

doyll · Dec 18, 2013

Quote:

Originally Posted by TiezZ BE

my asus p8p67pro has auto detect on the 4 pin chassis header, if I connect a 4 pin pwm fan it will provide pwm control. If I connect a 3 pin fan it will provide voltage control to adjust fan speed.

That Asus Maximus Hero you got is higher end than mine, I would be surpised if it didn't provide auto detect or at least a bios setting to set the control type of the 4 pin chassis header. Don't know if cpu header will do the same, never tested that with my board.

Have you actually tested it using a 12v power lead to fan instead of the motherboard fan header? Fan will give similar performance PWM or variable voltage. Asus has 4 pin headers and says it's auto detect but that does not mean it is really PWM. Asus even lies in some of their motherboard manuals showing 4-pin SYS fan header pin-out as PWM and users have found that they in fact are not PWM!

TiezZ BE · Dec 18, 2013

hm good point, i didn't test it like that...

I could also test if it follows the stated pwm curve of the noiseblocker pwm fans. If it's voltage regulated it would go more gradually if i'm not mistaken, if I add little bit more % on the fan power (manual fan control), if it's really pwm controlled it should go like this: 0% 600rpm - 25% 900rpm - 50% 1100rpm - 75% 1300rpm - 100% 1500rpm

Zipp · Dec 18, 2013

Quote:

Originally Posted by doyll

Easy way to find out if SYS fan headers are variable voltage or PWM is check the voltage on power pin.. pin-2. If it is PWM it will have 12v to it all the time. If it's voltage control the voltage will be 12 volts at full speed and lower voltage for lower speeds.

I use a PWM splitter with molex/sata power connecter and fan socket for splitter fan connector for PWM and RPM. If fan spins full speed all the time the header is not PWM.. no 12v power pulse.. only contant 12v so fan spins full speed.. If it lows down and speeds up it is PWM.. the 12v power is being pulsed to control the speed.

Chassis controls are probably variable voltage so yes, they will work with normal 3-pin fans.

If your radiator fans are moving faster why not have case fans that are supplying the air to them move faster too?? Running same number, type & speed case intake fans as radiator exhaust fans sounds logical.. It means the case intake is supplying similar amount of air into case as radiators fans are pushing out of case.

I didnt plan on having the exact same fans as case fans and radiator fans - I will, at least to begin with, use the stock fans for h100i, and then I thought about getting some more quiet fans as case fans - like the AF120 or AF140 Quiet and/or SP120 Quiet. In any case I won't have the same fans everywhere to begin with, as I would then have to invest in new fans for the H100i too

I was also planning to use the H100i as intake in the roof, not that it changes anything, but that was my plan

However, I would actually have enough headers if I could just use the 2 radiator fans on the same cpu header with a pwm splitter. Which sata PWM splitter are you using?

I also found this http://www.tomshardware.co.uk/answers/id-1744859/case-fans-pin-motherboard-pin.html#11219056 where it seems like an Asus representative says that the chassis fan headers are only voltage regulated, and not pwm - It sounds like it goes for all their motherboards.

TiezZ BE · Dec 18, 2013

nice to know

doyll · Dec 18, 2013

@ Zipp
I would suggest Gelid 4-way PWM splitter or Swiftech 8-way PWM hub. Both can be had with molex or sata connectors.

@ TiezZ BE
The only ways to test is knowing there is 12v going to fan from pin 2, knowing the PWM signal is in fact being supplied by pin 4 or that the voltage going to fan from pin 2 is changing as fan speed changes. Changing rpm curve based on % is just guessing.. and often fan do not spin at the prescribed 20% of 1000rpm full speed being 200rpm. I've found both voltage and PWM control to often not really use the rpm to set the fan speed... but to simply have pre-defined voltage or PWM signal assigned to the percentage point. You can verify this by putting something in front of fan. If the speed changes and does not come back to original speed it's not being controlled by rpm.

TiezZ BE · Dec 18, 2013

Zipp's kind of answered it already in his last post

doyll · Dec 18, 2013

Quote:

Originally Posted by TiezZ BE

Zipp's kind of answered it already in his last post

"it seems like an Asus representative says that the chassis fan headers are only voltage regulated, and not pwm - It sounds like goes for all their motherboards." Bold text parts don't sound like it's answered to me, but whatever.

"kind of answered" with statements "seems like" and "it sounds like"...

TiezZ BE · Dec 18, 2013

it's 'close enough' for me, I may it test when I change my fan setup and/or cable management.

I never 100% trust info online that's why I used that bold text part

btw: thx again for the info when I was setting up my fans in my new case, my rig runs nice and quiet in idle and while gaming the cpu is 2-4c cooler and GPU 3-5c cooler and fans aren't going 100% with my fan profile, so noise while gaming is also lower than before

Zipp · Dec 19, 2013

Quote:

Originally Posted by doyll

@ Zipp
I would suggest Gelid 4-way PWM splitter or Swiftech 8-way PWM hub. Both can be had with molex or sata connectors.

@ TiezZ BE
The only ways to test is knowing there is 12v going to fan from pin 2, knowing the PWM signal is in fact being supplied by pin 4 or that the voltage going to fan from pin 2 is changing as fan speed changes. Changing rpm curve based on % is just guessing.. and often fan do not spin at the prescribed 20% of 1000rpm full speed being 200rpm. I've found both voltage and PWM control to often not really use the rpm to set the fan speed... but to simply have pre-defined voltage or PWM signal assigned to the percentage point. You can verify this by putting something in front of fan. If the speed changes and does not come back to original speed it's not being controlled by rpm.

Do you think there are any quality differences? The Swiftech one does look quite nice though

Do you happen to know a European retailer that got this splitter?

The Asus guy in the link I posted wasn't vague in his statement about the fan headers, that was just me

- but still, that doesn't make it true

How should I connect the fans? Not enough headers on motherboard

Zipp

bombastinator

Enrainn

Zipp

Enrainn

doyll

Zipp

doyll

Zipp

doyll

TiezZ BE

doyll

TiezZ BE

Zipp

TiezZ BE

doyll

TiezZ BE

doyll

TiezZ BE

Zipp

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