One GPU turns on and off when rendering

[antisant]

I'm running 2 x 1080ti's with Octane VR.
I'm rendering a final image so i want maximum power for rendering. Ive got my render priority set to 'HIGH' and I've turned off "use priority" for both cards. (I've also got "use all GPU's" checked in the render settings for good measure)
however when i render to both the picture viewer and the Live Viewer one of my gpu's will turn on and off. it will jump between 0% usage and then up to 97% then back down to 0%. it does this over and over until the render has finished.
is this normal?

[aoktar]

It depends to scene. Have you experienced different scenws and kernels?