XPS 15 9560 FPS drop (Fortnite)

Hey everyone,

So when I play Fortnite in 1080p with 60fps and very low settings, I often get FPS dropdown (often goes to 20 or 30FPS) Even when I play in 720p.

I know there are several posts on it, I have tried many things such as formating, changing the performances in the settings, unplug/replug the battery, following what people advice to do, all to no avail.
I am about to once again contact Dell once and for all to ask them to change the motherboard as it seems the problem is coming from this hardware.

But before I do so, can I please get your advice on it ?

Thanks a lot !