Splicing Fan Connectors?

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the.ronin

Limp Gawd
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Mar 25, 2008
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Any issue splicing a single case fan connector into 4 connections? Specifically I'm just soldering the red, black, and yellow wires of a 3-pin remale fan connector to 4x 3-pin male fan connectors (so I believe this is in prallel - e.g., all red spliced together at some point of contact). I have a budget mobo with only 3 fan connectors. I plan to use the CPU fan to power the H60 cooling pump and a separate fan connector for the 120mm rad leaving me only 1 extra fan connector to power 3 other 120mm case fans. I'm adding an extra connector just in case. I guess my primary concern is whether all the fans will get appropriate power from the splice?
 
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Four fans is pushing it, IMO, but it might be okay depending on a couple things.

Each fan will have an amperage rating, probably stamped on the back label. You can usually depend on a motherboard fan header to supply one amp before bad things start to happen. Sometimes you can find specifically how much amperage your fan header can supply in the mobo manual, but not always. So, 1a is a safe guess.

If the amperages of your four fans added together are greater than 1a (or greater than the listed amperage rating, if that's available) you run a real risk of frying that header.

If it were me, I'd look into a fan controller or even just a splitter that your plug into a molex off your PSU.
 
Thank you! This was exactly my concerns. These are 120 Noctua fans so I will check the amperage. If I go molex route though they will just spin at 100% correct?
 
the.ronin said:
Thank you! This was exactly my concerns. These are 120 Noctua fans so I will check the amperage. If I go molex route though they will just spin at 100% correct?
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you can always use a cheap fan controller.. there are 20$ - 30$ fan controllers with lot of features and many sensors which are always helpful if you want to control based on temperatures... if you have a cheap motherboard it's already a risk the use of more than 2 fans, all the fans will receive the appropriate power, however it will cause overheat in the voltage regulator of the mobo, specially if its PWM, the header itself will be overheated, as also the main connector will be, so may end with just a header broken or with an entire mobo damaged.. definitively not recommended, as even on high-end boards i don't recommend to go beyond 2 fans per header unless they are very very low power fans.
 
the.ronin said:
Thank you! This was exactly my concerns. These are 120 Noctua fans so I will check the amperage. If I go molex route though they will just spin at 100% correct?
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Yes, but there are tricks you can use. Inline resistors are readily available to slow the fans, and molex connectors can be wired for 7v operation (which will also slow the fans.)

One of my favorite solutions to this problem is a Phanteks product, the PH-PWHUB_01, which will use one PWM signal from your motherboard and a separate SATA power connection to drive up to 11 3-pin fans.

Of course you can get even fancier with standalone fan controllers that work on manual knobs or even have temperature probes for automation, but those often mount in one or more 5-1/4" drive bays.
 
you will be fine with those, they are really efficient fans and the power consumption it's really low, typically fan headers go up to 1Amp for chassis fan headers, and 1.5Amp for CPU Fan headers (to mobos that use CPU Fan + CPU Opt). so overall you will be more than fine with those fans.
 
the.ronin said:
Thank you! This was exactly my concerns. These are 120 Noctua fans so I will check the amperage. If I go molex route though they will just spin at 100% correct?
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All the Noctua fans I've purchased came with Low-Noise Adaptors to slow them down, or do as VanGoghComplex said and mod some molex
 
Just don't splice the rpm wires. That can cause issues. Take the rpm from one fan, then splice the ground and voltage wires from all fans.
 
Pandur said:
Just don't splice the rpm wires. That can cause issues. Take the rpm from one fan, then splice the ground and voltage wires from all fans.
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Oh shoot I didn't think of that - I did splice all the yellows together. I'm guessing the other yellow wires don't even need to connect right since it's just sending info?
 
the.ronin said:
Oh shoot I didn't think of that - I did splice all the yellows together. I'm guessing the other yellow wires don't even need to connect right since it's just sending info?
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What will happen if they're all connected is that your header will be getting rpm info from all the fans at once. The reading will be really jittery and seldom accurate, which, depending on your mobo, may interfere with speed control.

You do want at least one connected though, or you won't be able to see speeds at all. Since they're all the same model fan and will be getting the same voltage from the header, you can safely assume the speed of one is a close-ish approximation for the speed of all.
 
The fans in link you posted are PWM. If they have 4-pin plug they are indeed PWM, and can use a PWM splitter with Sata or Molex power connector to PSU and 4-pin PWM and rpm signal control plugged into motherboard.

Also, fan power ratings are often very misleading because they are often running load rating, not startup / maximum load rating. Startup / maximum load rating is load motor uses when fan starts up or if impeller is stopped with motor running .. which can easily be 3x-5x higher load then running load rating is.

Here is Nidec Servo specs for Gentle Typoon fans that used to be sold by Scythe. You can see how much lower running load is then startup load.
upload_2017-12-2_12-27-24.png
 
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