I have really weird problem! Can anyone help me please?

When I put all 4 gpu, 1 of them have 0Mhz both GPU and Memory clock and gives 4mh/s. When I try 3 of them, still one give 4mh/s. And again when I try with 2 of them, one still give 4mh/s. BUT when I try each gpu separately they ALL work normal. Any ideas? Also almost never same gpu give 4mh/s.
Thanks in advance.

My rig:
Mobo: MSI Z170A GAMING PRO CARBON
GPU: 4x Sapphire RX 470 4GB GDDR5 NITRO+
PSU: EVGA 750 GQ
CPU: G3900
RAM: HyperX 4GB Fury DDR4 2400MHz CL15
SSD: KINGSTON 120GB HyperX Fury