Low GPU usage on 1080Ti

[ANTONBORODA]

Title says, my config is:
Core i7 6700k, Asrock Z170 Pro4/D3, nVidia GTX 1080 Ti.
I can barely get my CPU usage over 25-30% with anything. I tried games, benchmarks, pretty much anything except for heaven benchmark can't get over ~30% GPU usage. I thought this is some kind of measurement problem, but heaven can get it to ~100% and Valley get's it to ~60% so this does not appear to be a sensor problem.
Maybe I did something wrong? I have latest nvidia web drivers installed and acceleration is actually working properly, it's just the usage that's borked.

Any idea what can I do?
Or is this considered normal?

Thank you.

 

[ANTONBORODA]

Today, I was messing around and noticed that when I set my display to scaled (I have a 4K monitor) with full 4K resolution, GPU usage goes to 100% everywhere and this actually IMPROVES performance over the "Default for display" setting. I tend to have 20-30 FPS more on scaled resolution with 100% GPU usage than I do for "Default for display" with reduced GPU utilization for every single test I did, so this is not a single app feature or anything.
What could cause this? Because this appears to be an OS limitation of some kind and I'm unable to find anything remotely related to this.