Question LED fans too dim when connected to motherboard, brighter from Corsair H80i

Mar 23, 2020
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I recently installed a few LED fans to give my PC a bit more colour and lighting. The fans are 3 pin, are connected to my motherboard 4-pin PWM-capable headers. However I'm finding i have to ramp up these fans to 70-80% to get any light out of them, and it's just too loud. Now I understand that the fan speed would be controlled via voltage, and lowering voltage will dim the LEDs as these fans are 3-pin and not PWM capable. Makes sense.

But here's the thing,

I have one of these LED fans connected to my H80i, and even at 40% fan speed, this same fan is nice and bright! Not as bright as 100% but absolutely bright enough to look nice, without being able to even hear it.

What kind of method does the H80i use to control fan speed? Some kind of PWM but for a 3-pin which maintains a higher voltage? I'm trying to replicate this for my other fans so I can have them lit up without having to ramp my fans to full, but I have no idea what is going on. Any ideas would be apprechiated!
 
Mar 23, 2020
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Just an update if anyone is interested.

I have managed to repair my case fan controller. It uses an NE555 precision timer chip, which I believe is a form of PWM. Haing connected the fans to this, the LEDs are nice and bright, just like my H80i water cooler, even on low fan speeds. I can only assume that the motherboard voltage controller was too low for the LEDs to be visible on slower speeds. PWM seems to be the way to go for maintaining the voltage the LEDs need.
 

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