How many fans can I run off one fan header?

Trieclipse

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Aug 9, 2016
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Hello,

I built an ITX build in a Cooler Master NR200 ITX case about a year ago. The system has never had very good cooling in the time that I've had it. The build features a Ryzen 5 5800X and a Gigabyte GTX 3080 Ti, so it puts out a lot of heat. For CPU cooling I have the NZXT Kraken X63 280mm AIO. My main issue is that the radiator exhausts out the side of the case, and the inside fills up with the hot air coming off the RTX 3080 Ti.

A further infuriating issue is that the motherboard that I got - a Gigabyte X570-I AORUS PRO WIFI - only has one usable fan header. There are a total of three listed on the spec sheet, but one of them is reserved for the tiny fan that cools the chipset and NVME slot, so that's out of the question. A second is defective in that it runs my fans at 100%, with no discernable way to control the fan speed.

That leaves me with one fan header to potentially run 6 total fans - 2 on the rad, 2 at the top of the case, and 2 at the bottom, and the AIO pump. Right now I'm just making do with the AIO and one fan at the top, with the side panel off to exhaust hot air from the GPU.

So that brings me to my question - how many total fans can I run off this header by using splitters? Can I chain the splitters themselves (Noctua NF-A12x15 fans have disgustingly short connectors)? Is it dangerous to have the AIO pump also be connected to these splitters?

Thank you.
 

Enigma

Gawd
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Oct 15, 2003
Messages
872
Most fan headers support 12watts of power or 1 amp of draw. So the main rule of thumb would be you can load the header up to about 75% (fans pull more power when they start up than what they do when the are running full speed) This will give you some headroom so that you dont burn out the circuit.

Personally I dont like running more than 3 fans per header... Like stated above if you are running a pump I would run it straight off of the PSU.

According to Noctua those fans pull .13 amps or 1.56 watts. so 12 watts / 1.56 = 7 fans that would leave you about .5 watts in reserve. I would only run 6 fans max. 6*1.56=9.36 watts That would put you @ about 75% of the max draw on the header if it is in fact rated for 12 watts or 1 amp of draw.
 
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pendragon1

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Oct 7, 2000
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something like that^^^^

ive got 5 p12/p14s on one header...
you aio pump needs its own connection, run it off the psu then.
 

Trieclipse

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Aug 9, 2016
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First off, thank you all for the replies so far. I don't visit the forum often but I always appreciate people sharing their time and knowledge to help others out.

The pump is powered by a SATA power connector drawing power from the PSU, it's just the header that controls the pump speed which needs to be included in my fan header chain. My main concern with running fans or the pump off the PSU is losing the variability to adjust to temperature changes. I may need to keep the pump connected to CPU-FAN and invest in a fan controller that lets me control the fan speeds again by limiting the power or signal coming from the SYS-FAN connector on my motherboard. That's the one which runs all fans at 100%. It sounds like I should not try to run pump + 4-6 fans off just the CPU fan header.
 

pendragon1

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it's just the header that controls the pump speed which needs to be included in my fan header chain.
no, you do not want to hook it up like that. it should be at full speed with just the sata power, leave it like that. your fan headers just need to be set correctly, none are full speed only. put your pump on the sys-fan, and the fans on cpu-fan.
 
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Trieclipse

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no, you do not want to hook it up like that. it should be at full speed with just the sata power, leave it like that. your fan headers just need to be set correctly, none are full speed only. put your pump on the sys-fan, and the fans on cpu-fan.
The manual for the NZXT X63 states to plug the 3-pin Pump tach cable directly into the 4-pin CPU-FAN header on the motherboard. Is this an incorrect way of doing it? Is it better to leave the Pump tach cable disconnected, or plug it into a SYS-FAN? Right now I do not have the 3-pin tach cable connected directly into the 4-pin CPU-FAN, but rather have the CPU-FAN split 4 ways with the pump tach, 2 radiator fans, and 1 case fan all powered off of it, and SYS-FAN unused.

I will try the SYS-FAN header again, it's possible I was doing something incorrectly when I did the build.
 

Enigma

Gawd
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872
The manual for the NZXT X63 states to plug the 3-pin Pump tach cable directly into the 4-pin CPU-FAN header on the motherboard. Is this an incorrect way of doing it? Is it better to leave the Pump tach cable disconnected, or plug it into a SYS-FAN? Right now I do not have the 3-pin tach cable connected directly into the 4-pin CPU-FAN, but rather have the CPU-FAN split 4 ways with the pump tach, 2 radiator fans, and 1 case fan all powered off of it, and SYS-FAN unused.

I will try the SYS-FAN header again, it's possible I was doing something incorrectly when I did the build.
That cable is specifically for monitoring the pump speed nothing else... If you split it with the fans that "tach" will pick up that faster speed E.G. the fan speed.... I would monitor one or the other dont try to monitor both it will give you a bad signal/reading.... That 3 pin connector will not draw any current you can hook it up with a splitter but the readings in the kracken software will be off. The pump gets its power from the sata connector as stated above.
 
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doyll

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It's not something that can be stated without knowing what fans' amp load rating is. While most fan headers will handle up to about 1amp / 12w, problem is most fan amp ratings are running amp load, not startup load. Startup load is 2-4 times higher than running .. which is why most fan header failures are noticed at or shortly after turning on / starting system, not hours after it was started.

I you are using PWM fans there are PWM hubs with PSU power lead. These use PSU power and control fan speed with mobo PWM control. These work for 5-8 fans per hub / PWM source. More and sometimes some won't change speed like they should.
 

cyclone3d

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Aug 16, 2004
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On my new setup, I ended up buying some PWM fan hubs. The sense and PWM wires hook to the motherboard so they can be speed controlled by the motherboard and the power is drawn from a molex connector.

The fan hubs support up to 10A total on the hubs that support 10 fans.

They are pretty cheap and work great.... About $8 shipped on eBay. You can get either SATA or molex connector style for the power. I would highly recommend the molex ones as SATA connectors are not good for high amperage power draws.
 
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I have a built-in fan controller on my case which has 5 leads. I have spit off each lead with a 3x splitter for 14 fans for all my rads. Words perfectly and even scales up down in speed/voltage as if they were just connected to 1 fan but split into 3 each. No prob for years.
 
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