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LL120 Fan issue.


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So I built a new rig and I’m having issues with three of my LL120 fans. 2 will not light up and 1 lights up with a single green led. The LL120 fans spin and blow air without issue. 

The equipment Im running:

1x Corsair commander pro

2x Corsair RGB hubs

4x Corsair LL140 fans

3x Corsair LL120 fans


The LL140 fans all run perfectly. The LL140 fans are holding spots 1/2/3 on the first rgb hub. And spot 1 on the second RGB hub. Each rgb hub is plugged into the led ports on the commander pro.

the LL120 fans are holding spots 4/5/6 on the first Rgb hub. 

I have tried switching the LL120 fans and LL140 fans around to different sports and in different orders on the RGB hubs. No change. No matter the order, the LL120 fans don’t light up (aside from the single green led on the one fan) but the LL140 fans work perfectly no matter what order I put them in on the rgb hubs. 

I then switched the Rgb hub#1 with rgb hub#2 and did the same tests by switching the fans to different ports. No change. LL120 fans won’t light up but the LL140 fans do light up no matter what spot on the RGB hubs they are in.

My first thought was I had three bad fans. The LL120 fans spin and blow air no problem but won’t light up.

I put the LL120 fans onto a led port on the motherboard and they work! From the mother board they light up and change colors without issue.

so then I wired in a lighting node pro and wired the two rgb hubs to the led output connections. No change. 

ICUE shows the commander pro and the (node pro when it was connected) and  I can change the colors of the LL140 fans without issue but no color appears on the LL120 fans.

so now I’m lost. Any help would be greatly appreciated. 

picture: shows the 3 LL120 fans. The middle shows the single green led and the two outside ones are not emitting any light (light seen is from the other fans) 



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Ok so I did a bit more messing around with it.

The rgb hubs work in series as I’m sure you all know. Example:

port 2 on the rgb hub only work if port 1 is plugged in.

port 3 on the rgb hub only works if port 2 is plug in etc

If I plug one of the LL120 fans into port 2 on the rgb hub with a LL140 in port 1 and a LL140 in port 3, the port three LL 140 fan stops lighting up. 

but again if I plug then LL120 fans into the motherboard the leds work fine. So I’m guessing it ls the pin connection on the LL120 fans? They appear fine and not damaged. Seems odd for three fans to sustain connection damage..

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Yes, the fans work in series.

The data signal comes into the hub and then goes to fan 1. Fan 1 then returns a data signal back to the hub and then it gets passed to port 2. And so on and so on. So one bad fan can hurt the whole bunch. You've mentioned reordering them ... that's how you'd determine which fan is bad.

Like this:

Fan A on port 1. Does Fan A fully light up? If yes, put on port 2.

Fan B on port 1. Does Fan B fully light up? Does Fan A fully light up? If Yes to both, this is known good.

And so on ... ending with Fan A on port 1 and a Good fan on Port 2 ... to fully validate Fan A.

Note that for it to be good, it has to pass the signal to the next.

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How are you plugging it in to the motherboard?

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