Game stutter (still images for 1sec)?

The days I bought a new graphics card the 3060ti and installed it 2 days ago and before that I had a 1060. Sometimes I have a very fluid picture but then, for example, I play Fortnite and in a fight I get a freeze frame and, for example, when you are in the world at the very beginning it breaks down something but only rarely. Does anyone know why that could be because before that I always had a fluid picture with the 1060.

Which processor is installed?

Then my first question is, why do you get new hardware when everything is working?
2. Have you updated all drivers and reinstalled them if necessary?

Amd ryzen 7 3700x

I also wanted to play other games like warzone

What did you do after installing the new card? Deleted all drivers of the old?

Yes had deleted the driver before and now loaded a new nvidia driver on it