When I press launch in the game room, GPU immediately rushes to 100%. This is even before we click ready and start playing. GPU continues at 100% (even if I cancel the game) untill I press Exit in the Main Menu. After exit it drops to 0-1%.

What can I do?

I think the problem started after upgrade from Windows 7 to Windows 10. Perhaps directly, perhaps after a Windows 10 update - I didn't play often when Windows 7 became unsupported. I've tried reinstalling a clean Windows 10 installation but problem persists.

I play on MacBook Pro retina 2012 (original Mac OS) with BootCamp 6.0, 8 GB RAM. Graphics is NVIDIA GeForce GT 650M with 1,0 GB memory. Original res is 2880x1800, but 1600 x 1200 doesn't help either. I've tried some settings in the NVIDIA control panel, but have honestly no clue what I'm doing.

The MacBook Pro has still great specs, and playing Titans has never been a problem. Even 100% GPU doesn't seem to affect gameplay or lag, but fan races constantly and it can't be good for my graphics card.

Thanks!

Update:
Actually 100% GPU is in the start menu. When I click Ok and the game starts, GPU drops to about 50-60% and continues until resign or victory. Then up to 100% again until I quit the program.
Strange that gameplay is better than menu. Could there be a bug in the tweak to 1600x1200 from original 1280x1028? Or is it my GeForce drivers?