Sapphire RX 470 Nitro (non+) power fluctuation

Hello friends, i have a rig with 6 Sapphire RX 470 Nitro (non+) with 1100/2000 Mhz and power from 85-95 watt maximum.
Recently i have seen a fluctuations in my cards power like in the photo below. Does anybody know what can cause this and what will can i do to have the power stable? I have tried to decrease/increase the clock/memory but the fluctuations persist.
Thank you