Author Topic: How many fans per FAN header?  (Read 170 times)

tle

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How many fans per FAN header?
« on: May 20, 2020, 10:41:48 am »
I am planning to revamp my chassis cooling so I am wondering how many fans could I split from one fan header? There is no mentioning how many amps per fan header in the service manual btw.

Much thanks in advance
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ClassicHasClass

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Re: How many fans per FAN header?
« Reply #1 on: May 21, 2020, 02:44:16 pm »
I've used a single splitter without problems. I think it would get dicey chaining more than that.

surf

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Re: How many fans per FAN header?
« Reply #2 on: May 21, 2020, 04:05:48 pm »
I'd guess an amp would be about as much current as you want to pull through a regular header pin.  If your fans are high power, you could always source the power straight from the PS and the PWM signal from the fan header.

MPC7500

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Re: How many fans per FAN header?
« Reply #3 on: May 21, 2020, 04:55:06 pm »
Hmm, I never thought about that. In my BB I have five fans in total.

2x Silent Wings 3 PWM High-Speed, 140mm (1.68W/ 0.5A max.)
3x Silent Wings 3 PWM High-Speed, 120mm (1.92W/ 0.37A max.)

Would be good, if madscientist159 could comment on that topic.

Till now no problems.
Or maybe someone could look at the schematics? Sadly, I have no working optical drive.

madscientist159

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Re: How many fans per FAN header?
« Reply #4 on: May 22, 2020, 12:52:00 pm »
So if you look at the schematics, you can see the fan power pins are wired straight to the main +12V supply rail.  This in turn is normally provided through either a power plane or a fat trace, meaning the power limit will be the fan header itself -- in fact, given the fan power header is comprised of standard stake pins, the power limit is more precisely in the fan connector itself.  Many of the cheapest Chinese fan connectors appear to use non-soldered (crimped) connections to what seems to be horse hair instead of copper wire, meaning I would be very concerned about pulling even an amp though them.

If you can get a high quality connector, the fan headers themselves are likely good for ~5A.  Problem is, if your connector melts down / catches fire, it will damage the header and the PCB, and that would not be covered under warranty, so please be sure of the quality of the mating connector before trying to pull 5A...  ;)

tle

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Re: How many fans per FAN header?
« Reply #5 on: May 23, 2020, 10:22:08 am »
Thanks for everyone's response.

I would not risk hooking up cheap fans into one same fan header nor having a total of more than 1A (from what I read 1A is a safe threshold...).

Alternatively like surf has suggested, I could use the PSU to power my fans instead, I guess it would be much safer.

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MPC7500

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Re: How many fans per FAN header?
« Reply #6 on: May 23, 2020, 11:43:46 am »
I don't think this will make any difference. Because the bottleneck will still be the Y-cable and not the fan connector itself.

tle

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Re: How many fans per FAN header?
« Reply #7 on: June 12, 2020, 01:50:13 am »
I would like to let everyone know that there is no issue of chaining three Noctua NF-A6x25 (PWM version) fans in one header.
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