Thank you for your kind answer. Well I'm not so concerned about my temps, think they are still good on my rx580s and also got some reserves left. But the fans came along with the rig so I'll give it a shot and see how much I can benefit or not
However I just don't know what's the best way to control the fans, you think it would work with a small fan controller and chainlink all the fans to one channel? Since psu not possible (no control, 100%) and on connected to the board they won't start.