I've been having some severe FPS issues with my xps 15; I struggle to play games, an example being fortnite. I've been trying to play in the lowest graphics possible with a resolution of 1080p. For a few minutes it jumps around 70-90FPS, and then it dips after that to anything from 20-50 FPS. I tried lowering the resolution to 720p and there was no change in FPS. I've updated my BIOS, the drivers, made sure the 960M is being used instead of the integrated graphics. I'm not sure what else to do.