When I render my animated scene with Blender (2.80 beta from 10-5-2019) Cycles using "GPU supported feature set" I only get to about 10-25% GPU utilization on my Nvidia GTX 970 on Windows 10. I've also tried it on a build from a month ago, same result. Both task manager and CPUID Hwmonitor give me the same number. The scene contains a homemade HDRI.
How can I get it to use more of my GPU? I just ordered another GTX 970 but seeing how it's not even using this one it's probably going to go unused. Would it help to switch to Linux so there's no Windows layer in between? I've tried to change the tile size but that just makes it worse (smaller or larger than 64).