Commander Core XT - Weird Fan Behavior

[Linition]

So I just installed this hub and I have 2 fans behaving weirdly.

I got 2 beQuiet Silent Wings 2 120mm, 1 beQuiet 140mm and 1 ML120 installed, all of them PWM.
The 2 120mm Silent Wings 2 don't seem to work right.

One of them, when set to zero RPM mode, keeps spiking to 4 RPM every few seconds in a steady interval, the other refuses to go below 355 RPM even when I manually flatten its curve to 0.

[LeDoyen]

very low speeds are hit and miss depending on the model.

Some fans will have a zero RPM mode and will stop below a certain PWM%

Some others will maintain a mimimum speed if PWM drops way down.

Are those two fans on a splitter ? or discrete ports for each?

 

[Linition]

10 minutes ago, LeDoyen said:

very low speeds are hit and miss depending on the model.

Some fans will have a zero RPM mode and will stop below a certain PWM%

Some others will maintain a mimimum speed if PWM drops way down.

Are those two fans on a splitter ? or discrete ports for each?

 

I used to use a splitter before I did the Commander.
I am always suspicious what sub-optimal power does to electronics, maybe it messed with them, but now they are all on individual Commander ports.
I noticed strange behavior of one of the 120mm and the 140mm fan before when I used to control them via Asrock's supplied fan control. When below a certain RPM % they would make weird double-clicking sounds which I couldn't explain, but I thought to myself the fan power supply on the board might be poor quality and maybe running into too much resistance, which is one reason I decided to get the Commander.

I also got rather dirty power, I think, which is why I use a special power hub to deal with power spikes, but my computer has been running exceptionally stable for years so I can't imagine that being the cause.

[LeDoyen]

i never used bequiet fans but the arctic P12 i tried also went to stupidly low RPMs like these, and i remember having a fan sometimes doing that, slowing way down and kicking back in.

Since they don't seem to have a zero RPM mode, i would see what their minimum stable speed is and run them just a hair faster to get the speed stable.

Fans don't care much about bad power. as long as you have roughly 12V they will work fine. The problem seems to be speed stability at very low speeds. That's probably why most fans don't go below 5 or 600 RPM.

Now remember most of that stability comes from the fan embedded PWM driver, not from the fan controller, unless it's really thrash 😛

 

When you talk of bad power, what is it exactly? you have a very old PSU ?

[c-attack]

The SW2 and SW3 fans historically have some PWM issues on Corsair controllers.  Most do not work on the AIO fan controllers.  The Commander Pro has a somewhat better success rate, but there definitely is some type of spec issue between some of the 'European' designed fans and the Corsair controllers. BeQuiet, Vardar, and Noctua come up regularly.  I have not tested the Core/XT controller for these since most people with those are on RGB fans.  If you have enough of them to make it worthwhile, you can wash the signal through a PWM repeater.  This makes my SW3 high speed controllable from the Commander Pro.   

Edited December 18, 2021 by c-attack

[Linition]

Noctua? Oh dear....

Since you bring up "stable minimum speed", I think I finally discovered what the clicking sounds are.
At lower RPM they seem to randomly wobble and slightly nick the frame, and here I was getting paranoid over power issues...

Out of like 5 beQuiet fans I got 3 that have some kind of noise problems, whether wobble causes them to scratch on something or the bearings stop running smoothly.
And this is why I am so fascinated by the ML fans. Sure they are louder by default at certain RPMs, but what's the point of having theoretically slightly quieter fans when they end up making noise like that anyway?

Guess I will swap them all out for ML fans sooner rather than later.

[c-attack]

Standard Noctua do not have an issue. There are control problems with the Industrial line and internal fan controllers on most of the prior AIO models.