I have the following setup:

OS: EthOS latest, running fine with 3 GPUS
Motherboard: Asus Prime Z270-P
CPU: Intel i3
PSU: Corsair RM850
GPU's: Sapphire RX850 8gb

The rig has been working fine for months, just received my 4th GPU in the mail.
After plugging it in using this cable https://www.amazon.com/gp/product/B00A45JA52/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
All I get when trying to power up is a "click" from the PSU, and nothing else.

I disconnected the 4th GPU, and now only running with 3 cards.

Would there be a problem with running 4 GPU's on an RM850 ?