Will my motherboard sys fan headers provide enough power?

Will my motherboard sys fan headers provide enough power for two case fans on one header?

My mobo has 1 x CPU Fan connector, and 1 x Chassis Fan connector, but my case has two fans. If I use a 3-pin cable splitter, can my motherboard handle the power of two fans on one header? And If the Mobo can handle two fans, will the speeds of the fan still be controllable with a splitter?

I have a 620w PSU, and an Asus B85M-G Mobo.

These are the parts I have.

Any help would be appreciated.
2 answers Last reply Best Answer
More about motherboard sys fan headers provide power
  1. I would just connect the second fan to the PSU directly I believe they are 3 pin fans anyway not 4pin PWM fans.
  2. Best answer
    Most motherboards are good for about 1 amp of fans(remember fans have a higher peek power that has to be taken into consideration).

    If the board can control with voltage(You have to watch this as some boards just run 3 pin fans full speed all the time even on 3 pin headers) then yes they would both be controlled with a splitter. It is best to contact Asus to see the current limit on the fan header of the board.

    PWM fans have the advantage of not requiring a regulator to lower the voltage for speed(they always get 12 and the fan controls speed with a pulsing duty cycle signal) reduction and should overall be cheaper to implement on the board.

    I have personally run multiple low speed fans off of a single board header without issues, but every board and fan combination is different.

    If you do use a Y cable, You would check if it has 2 speed sense(yellow most of the time, it is the third wire) wires and remove one to avoid speed misreads. I have no clue why they even make them this way to begin with(Noctua's included 3 pin splitter was built the right way).
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