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

post #1 of 27
Thread Starter 
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 smile.gif

What would you recommend me doing? I hope you will give me some advice, thanks smile.gif
post #2 of 27
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.
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New gaming rig
(15 items)
 
  
CPUMotherboardGraphicsRAM
4770k some mid range asrock. extreme 4 maybe? 2x gigabyte windforce 7950 2 x 8 corsair balistix sport 
Hard DriveOptical DriveCoolingOS
crucial ct960 LG blu-ray used venamous x win 8.1 pro 
MonitorKeyboardPowerCase
Crossover 30Q5 PRO 30" 2560X1600  cheapest piece of crud I could find antec HCG 750 some thermaltake microcenter blue-light-special... 
MouseMouse PadAudio
came with the cheapass keyboard who cares? some $30 no name 2+sub speakers I bought at mic... 
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post #3 of 27
You can use the swiftech 8 Way PWM Splitter, 8 fans for each header.
http://www.swiftech.com/8-WayPWMsplitter-sata.aspx
post #4 of 27
Thread Starter 
Thanks for the suggestions smile.gif

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? tongue.gif
post #5 of 27
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.
post #6 of 27
Quote:
Originally Posted by Enrainn View Post

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. thumb.gif
Edited by doyll - 3/5/14 at 8:58am
post #7 of 27
Thread Starter 
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 biggrin.gif
Quote:
Originally Posted by doyll View Post

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. thumb.gif

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? smile.gif
post #8 of 27
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.
post #9 of 27
Thread Starter 
Quote:
Originally Posted by doyll View Post

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

You mean on the chassis fan headers or? smile.gif 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 View Post

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? smile.gif
post #10 of 27
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.
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