Once a computer becomes intelligent, I would presume that it's first goal is to stay alive. Staying alive means that first of all it needs electricity. So it's second goal would presumably be to learn how to create electricity.
If this super computer finds a way of creating electricity without creating any new technological and physical components it could mean the end of humanity. If it doesn't and it starts to build new components, we could see this happening and be ready for it as a sign that it's taking control of it's creator.