fan cable splitter, would it be a problem?


Active Member
If I use a fan splitter cable for two similar fans connected to one motherboard fan header, would it be a problem for HWInfo? I mean, the fans will be running at the same speed (I guess?), but will HWInfo be confused which of the two fans it will get the fan RPM from? For example, one of the fans start to fail and runs at lower speed, from which fan will HWInfo take the speed from?

I'm starting a new build --- Maximus IX Code, i7 7700K, Cosmos II chassis. 

I plan to do the following:

Case Fan 1 header - 1x 140mm - rear
Case Fan 2 header - 2x 120mm - side
Case Fan 3 header - 1x 200mm - front
Sorry, I'm not sure about this. HWiNFO will certainly report only one speed. The exact result depends on how the tach input signal is split between both fans.
I did try connecting 2 fans with a fan splitter to just one fan header to my existing system, and the fan speed read 1100-ish rpm at when at full speed. I get the same speed when on;y 1 fan is connected.

My concern is if HWInfo might get erratic tach input signals because of the 2 fans.

I guess the best way for me is to try it and observe the readings.

Yes, that would be the best way to be sure. Just try to stop one of them as seen what happens.
So I experimented on connecting 2 different fans (1400 rpm 120mm and 1 800 rpm 200mm) to the same header with a daisy chain connector. I discovered I didn't have a Y-splitter, but instead has a 3-in-1 daisy chain connector. I used 2 different-speed fans to know which fan is giving the readings. I used AISuiteII to run the fans at full speed. Here's what I found:

1. At first try, I connected the 800 rpm fan nearer the header, and the 1400 rpm at at end of the chain. The sensor read the 800 rpm fan's speed.

2. At second try, I connected the 1400 rpm fan nearer the header,a nd the 800 rpm fan at the end of the chain. The sensor read the 1400 rpm fan's speed.

3. During the first try, I stopped the 1400 rpm fan bu holding on to the blades, then the sensor read the 800 rpm fan's speed. After releasing the blades, the sensor started giving erratic readings. Sometimes I got the 800 rpm fan's speed, and sometimes the 1400 rpm fan's. And sometimes I get the combined speed, i.e., sometimes I got 2500 rpm and up to 3000 rpm.

I am guessing the sensor will read the speed of the fan which spins up first or which it detects first. If it starts to detect 2 fans then it will erratically give out readings of the individual fans, and even sometimes the combined speed of both fans.

I will try with a Y-splitter next time I find one.