UE4 not using all hardware resources

I’m rendering a Sequence video inside UE4.
Resolution 1920x1080, 60 frames per second, 100 compression.
So, I didn’t spare too much on settings. Yet, my hardware is not even breaking a sweat judging by the Task Manager.

Am I doing something wrong?
How can I make it use more resources?

Hardware:
CPU: Ryzen 1700X
RAM: 2 x 16GB
GPU: ASUS 1080 Ti