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wiring 3 pwm fans

drop4205
Level 12
I am just wondering how to go about hard wiring 3 fans on a radiator and solder the wires together "as one unit" so I dont need a
second connector to connect them. Do I connect all red and black together to a molex or sata connection then all blue pwm wires
to a fan header and only 1 yellow tach wire from 1 fan to the fan header? That way I can connect the fan header with yellow and blue
to one motherboard header?

Strix X870e-e / AMD 9800x3d / Gskill 32gb 6000 / Crucial T705 / ASUS Prime 9070 XT / Lian Li 011 compact / Lian Li Hydroshift AIO / Lian Li Platinum 1300 psu / Windows 11 24h2

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5 REPLIES 5

Ntwlf
Level 12
Hey drop4205,

You got it right, connecting them as you have indicated.

PWM fans always get full 12v power and ground (fan wires red "+" / black "-" respectively). On the PSU the yellow wire is 12v "+" , and the black wire is ground "-". Connecting these fan wires directly to PSU will eliminate concerns of overloading the mobo fan connectors if the number of fans connected exceeds the limits of the mobo specs (amp supply per connector). Then tying all the blue wires (PWM signal) to one wire and running it to the mobo connector, plus adding only one fan yellow wire (tach/rpm sensor) to the mobo connector.

The blue wire (PWM signal) from multiple fans connected together does not strain components on the mobo, but to many fans connected will cause a degraded signal to be received to be able to run at the speed the mobo is telling it to. I think 5 or 6 fans is the limit. If to many fans are connected the fans will run very slow if at all, but no damage will be done other than higher temperatures do to lack of air flow from slow or not running fans.

The yellow wire (tach/rpm sensor) can only come from one single fan for accurate sensing of the fans speed. Kind of like having a conversation with only one person in a crowded room where everyone is talking at once, it is difficult to discern what that person is saying. So the mobo can only be allowed to hear only one fan.

Nate152
Moderator
Hi drop4205 as Ntwlf says you got it right ! 🙂

Another easy solution would be this.

http://www.amazon.com/Phobya-3-Way-Splitter-Single-Connection/dp/B004CLFOK4/ref=sr_1_4?ie=UTF8&qid=1...

The motherboard fan headers are rated for 1 amp so as long as your three fans don't exceed this you're good to go.

drop4205
Level 12
thank you for the help Ntwlf and Nate. Trying to or thinking of doing a 360 rad open loop for cpu at some point then maybe add another 360 or 280 rad for my strix 980 that I have now. It runs great overclocked at 1530mhz on air for now. Not sure if I wanna keep the 980 or try and get a strix 980 ti

Strix X870e-e / AMD 9800x3d / Gskill 32gb 6000 / Crucial T705 / ASUS Prime 9070 XT / Lian Li 011 compact / Lian Li Hydroshift AIO / Lian Li Platinum 1300 psu / Windows 11 24h2

Nate152
Moderator
Whoa ! That's some MEGA hertz on your 980, you got a screamer. 😄

The 980ti is significantly faster than the 980, here are some benchmarks to give you an idea.