I currently have an RTX 2060 and an Intel Core i5 9400f. In Fortnite I only have a maximum of 144 FPS.
I currently have around 400 euro available, which I can either invest in a new processor or a new graphics card.
which of the two should I buy new and which model?
Graphics card is not worth it at the moment. The new GeForce cards will come out in 2 - 3 months, then the prices on the market will generally change and everything current will be cheaper.
So graphics card is still sufficient. Maybe a new processor. Eg I7-9700k.
Clearly your CPU!
Fortnite needs high single-core performance and unfortunately your i5 9400f doesn't quite have that.
My recommendation would be an i5 10600K with a cheap Z490 motherboard!
I would get a new processor. Since you probably want to stay with Intel, you can buy an intel i9.
That's exactly what I wanted to write.
Thank you. Now, unfortunately, I bought a new H370 motherboard a few months ago. My idea was to buy an I7 9700k. Do you notice a big difference to my current I5?
Hmm, the mainboard is not that good. But I do believe that the difference will be big.