Strong FPS drops in Fortnite with an RTX 2070 normal?

I have an RTX 2070 and had 5fps drops in Fortnite and now since I got a Displayport cable (on the day I also updated the Nvidia game ready driver and downloaded the update) I have strong fps drops of up to 70 Fps (play on 165). Is that normal? In addition, a friend of mine has a GTX 1070ti and only has drops of up to 180 fps (it plays at 240). What can I do against it? I have already tried to switch to DirectX11 but sometimes have drops of up to 30fps.

I have all graphics settings on low.

Processor = Amd ryzen 5 3600

The one friend with the Gtx 1070ti

Has an Intel core i7

Graphics driver uninstalled and then tried? That always gives me more fps

But do I need the driver? Or not?

No is also possible without

Ok, I'll try it, thank you

How warm is the CPU / GPU?

I think both are between 50-65 °

With which program and under what conditions did you measure it?