OP - I felt the same way, there was a buzzing/ticking/pulsing with all my fans, Noctua, Slipstream and the FT02 180mm case fans when controlled by the touch screen NZXT fan controller - no PWM here.
Then today I decided to run them all off the motherboard fan headers - then near silence! All of them running around 600-700rpm under auto control
Now there was something I thought was puzzling - when I used the fan controller to control the case fans, using the cable that comes with Sliptreams, that allows for RPM monitoring to a motherboard header - the RPM were bouncing all over the place, going up to 3000+ and back down to where they should be.
Ontop of that the speed settings for the FT02 case fans, which run in parallel with whatever your controlling them from, had no effect (they work when using the motherboard headers)
So that kinda clued me that something was not right....
It seems like the fans were pulsing on/off max speed in split seconds and thus buzzing!
I just thought it weird that all these fans have claims of 6-15db etc, which SPCR reviews and others here have claimed as really quiet, and yet didn't seem to jive with my reaility - now faith has been restored
So not all fan controllers are doing it the right way. I believe my old Zalman fan controller in my other old case, does not have this issue, I'll see when I swap it in