Finally found a working solution!

1. Open NVidia Control Panel
2. Manage 3D Settings
3. Program Settings
4. Select "ACValhalla.exe"
5. Select "High-perfomance NVidia processor"
6. Press "Apply"
7. Restart Game

@victuskristus

@dx2-lft May be this can help https://www.howtogeek.com/351522/how-to-choose-which-gpu-a-game-uses-on-windows-10/#:~:text=To%20assign%20an%20application%20to%20a%20GPU%2C%20head%20to%20Settings,application%20you%20want%20to%20configure.: (https://howtogeek.com/351522/how-to-choose-which-gpu-a-game-uses-on-windows-10#:~:text=To%20assign%20an%20application%20to%20a%20GPU%2C%20head%20to%20Settings,application%20you%20want%20to%20configure.)

It's same solution but more universal for Windows 10

Finally found a working solution!

1. Open NVidia Control Panel
2. Manage 3D Settings
3. Program Settings
4. Select "ACValhalla.exe"
5. Select "High-perfomance NVidia processor"
6. Press "Apply"
7. Restart Game

While in fulscreen mode, game stuck at Health Warning (some audio trying to play on background, but immediatly stops)
Attempt to change settings (WindowMode=0) in ACValhalla.ini lead to alternative behaviour with only black screen on game launch and no sounds