I have GPU rendering problem with some files because CPU, RAM and Hard Disk up 100% and when rendering finished is bad but with CPU is 100%, RAM stable and Hard Disk stable and rendering is good.
Windows 10 PRO 64 bits
I have 16 Gb ram intel i5-3570K
Nvidia Quadro P4000
I updated to graphic card’s last driver and this was tested on Sketchup 2016 and Sketchup 2017 with Vray 3.40.04. In Vray 2.0 GPU rending don’t run.
Can you share some screenshot of how bad it is?
Are you using GPU acceleration with interactive or progressive mode?
Note that not all features are supported with interactive mode yet. Check this: Supported Features in Interactive Rendering
Also note that CPU and GPU rendering might not be identical depending on your scene.