Question Need a very slight speed reduction cable for my AIO fans

[Fastfishy2]

Long story short, I have a 240mm AIO and both the fans on it are daisy chained to my CPU fan header for control. All other fan headers are in use. The reason for this is, I need all the fans in the case running at slightly different RPM otherwise they tend to "harmonize" and create this kind of oscillating humming, which annoys me when I hear it. Especially if the fans are of the same model and run at the same RPM, this humming happens. Might just be my sensitive ears.

Basically I need something like one of those Noctua low speed cables, but with less % of speed reduction because obviously I don't want one AIO fan running significantly slower than the other, just enough to avoid them being at the exact same speed. I was thinking in the range of 10% or less. Does anyone know any decent products that will let me do that? Sorry, I know it's very specific.

 

[BFG-9000]

The most reasonable solution is to cut the power wire of one fan and connect the ends with a through-hole resistor. Those resistor cables from Noctua or Gelid operate the same way but they have just selected too high a resistance for what you want.

Even turned all the way up to max, those inline PWM boxes like the old Zalman FANMATE 2, Gelid fan speed controller or the 4-pin Noctua NA-FC1 will all drop 200-300rpm which is more than you are looking for.

All of the commercial products have the advantage of simply plugging inline, but you could use solderless spade or bullet connectors on the resistor to allow for quick removal or changing of the value.

 

[Fastfishy2]

The most reasonable solution is to cut the power wire of one fan and connect the ends with a through-hole resistor. Those resistor cables from Noctua or Gelid operate the same way but they have just selected too high a resistance for what you want.

Even turned all the way up to max, those inline PWM boxes like the old Zalman FANMATE 2, Gelid fan speed controller or the 4-pin Noctua NA-FC1 will all drop 200-300rpm which is more than you are looking for.

All of the commercial products have the advantage of simply plugging inline, but you could use solderless spade or bullet connectors on the resistor to allow for quick removal or changing of the value.

honestly I don't trust myself to self-fabricate anything to do with electronics. I could do it, but I'd spend way too much time worrying about fucking it up.

I've had a think since I posted this and I do actually have one more PWM header available and it's in the middle of my motherboard. What I'm going to do is get a long 4-pin extension cable and have the second radiator fan hooked up to that, with a nearly-identical fan curve to the CPU header, except ever so slightly slower. That way they're basically both doing more or less the same cooling work, but never going the same speed (which causes the humming / oscillating noise)