Two separate solutions remove the noise..hmm. Maybe the source is the h100+fan and the side panel is just loose enough to enhance the vibration. When you touch the fan grills you dampen it and when you remove the side panel you dampen it.
What happens if you press against the side panel? (is it the side with the fan/covers? is that loose?) If that works, maybe you can just add a shim or two between the side panel and case.
I haven't tried the shim yet, i did try and press both panels but it didnt change anything, i ducktaped the grill on the side panel also but without sucess, when i remove the side fan panel, the pulsating sound changes to a faster speed.
I did notice though that i havent noticed before is that without the side panel the sound is still there but so faint its barely noticeable.
It could also be cavity resonance - the interior volume of air inside the case can sometimes resonate because of the fans. Is there one intake and one exhaust fan? Have you tried running the system with just an exhaust fan, or with a faster fan on one or the other position?
Yeah i tried all kinda combinations and used different speeds.
i tried the fans mounted between the h100 and the case also.
Im using 3 intake and 3 exhaust at the moment with some positive pressure. i also tried more exhaust but its the same.