Why is my high spec pc running like a potato?

My pc used to be able to run very demanding games like gta v in 4k, Battlefront etc.
I reset it to factory settings and now it can t even run simple games.

The specs are:
NVIDIA GeForce GTX 1060 6gb
16 gb RAM
Intel Core i7 -4790 3.60GHz
Probably missed something.
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