My Deco x3600 units make noise, and I'm wondering why. I have three x3600 units and two x25 units. The x25 are fine, but all three x3600 units make a faint clicking/scratching and or crackle sound when you are close enough to hear them. Hard to describe, but a click/static sound is closest I guess. It's faint, but I can hear them from a few feet away in a quiet room. Speed is all over, fast, slow, in between, no pattern. Put my ear up to then it's plain as day they are the cause, sounds louder to me near the top of the unit and fainter near bottom.

It's not a fan, it's not coil whine, and the more connected devices the more clicking they do. It is constant, and been doing in since I got them so it seems normal for these specific devices. I was thinking antenna switching or something as there are a bunch I know and it's near the top where I find it loudest, but who knows. I was just wondering why on earth it's audible in general. Strange to be able to hear solid state electronics working at all. 

I had to remove an x3600 and replace it with an x25 in a bedroom as it was driving me nuts at times. Almost asleep, nice and quiet and then I lay there hearing the router making noise.... grrr.

Just wondering, thanks!