Premiere pro not using GPU acceleration

Hi, all

We have recently upgraded our editing rig with the components listed below. Since then we have noticed that when watching and scrubbing through a 4k timeline we are seeing over 50% CPU usage but are only seeing 30% GPU usage at the most. We want to get the full potential out of our new hardware and have checked extensively through the settings in premier pro. GPU acceleration has been enabled and we have done lots of research already. Any help would be much appreciated.

System Specifications:

CPU: AMD Ryzen 7 1800x

GPU: Radeon Pro WX 7100 35

RAM: 32gb 3000MHz

OS: Windows 10 64 bit 1713.1

Thanks for you time,

LPSB Editing team