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Fan ML 140 Pro 4 pin Question on installation ?


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Hi I am Ash and I have a question please.

Corsair Link and Pro hardware

2 x 140mm ML fan

1 x 120mm ML fan

I am running Asus AI suite 3 with Fan Expert.


The Asus 170 pro motherboard has 2 x chassis 4 pin headers available these can be set to 1 Dc(CPU) or 2 Power Width Monitor modes for the ML series fans. Am I right to think that its PWM mode. For the 3rd fan I have a 4 pin CPU OPT or 4 pin Water pump header(seem to remember I shouldn't use that) and finally a 5pin EXT fan header. Would like some answers on the power state mode selection as I seem to remember the ML magnetic fan requires PWM mode and any ideas how to connect the third fan.

I look forward to your reply


Happy Christmas.

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Yes, 4 pin fans are PWM. The Z170 should auto-detect the type, but you can manually set it as well. The header selection is more complicated.


You don’t want CPU-OPT. The OPTional header is a mirror of CPU fan. It will do whatever CPU fan does. This is useful for dual fan air coolers, but much less so for case fans. CPU & OPT can only use cpu temperature as a control variable. This is too dynamic and not really appropriate for case fan control.


W_Pump or AIO headers are set and locked to 100% by default. This is intended to be used for water pumps. On some boards, you can unlock it and turn it back into a CHA fan header. However, once again you can only use cpu temperature as the control. It would be better if Asus gave you a standard CHAssis fan header instead.


Fan-ext is for a small fan circuit board that lets you control additional fans from one source. It is a powered splitter. Hard to find and not helpful for this.


What you really want is a standard 4 pin PWM splitter that will tie two ML fans to one motherboard header. ML fans have a very low current draw and this a very safe and common solution. It should be very inexpensive, but make sure you get a PWM splitter. It will have 1x3 pin connector and 1x4 pin connector. Both fans will run the same speed.

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