Speakers are constantly buzzing, or farting silently, funny thing is that whenever screen redraws buzzing sound is louder., eg. if I turn on some OpenGL demo it makes louder noises.

I've set up with two KRK rokit6s (active speakers) connected via RCA to out(green) on MB.
(KRK) (LCD) (KRK)

I know these are unbalanced outputs but I didn't have this problem with the other PC. I've checked all connections and tried two different RCA->TRS cables. I've tried also connecting laptop, no issues.

Also same GPU in the other PC and HD Audio plus KRK no problem.


Another things I've checked: separating power supply cables to other outlets.
PSU is no near MB, actuallly it sits atthe bottom of the chassis.

I have also tried to disconnect OC Key.

Setting up sound quality made buzzing a little quieter.