Getting random FPS drop on almost every game, not a throttling issue
Solution 1:
I had the same issue, and for me it was OneDrive, checking for something to sync. There was nothing to sync even, but it stopped when I closed it.
This happened to me in Heroes of the Storm, which doesn't need anything powerful.
I would imagine that any other cloudstorage could have same impact: DropBox, Google Drive, Amazon, ... you name it.
Ensure the app is stopped when playing (and not running in tray!).