It finally works here.. Speed is "ok" for RX 480's..

My Z170 only runs with 3 RX480s.. As soon as I put it int 4.th the board doesn't boot - it seems there is a conflict with the SATA port or so - no HD is recognized anymore. I already tried to disable the Internal GPU, HD Audio etc. everything in BIOS but it doesn't help.. Seems this shitty board can only run 3 cards at once.
did you update the bios? helps with some boards to get a 4th or 5th card working, what brand is it?