New Laptop lost extremly graphics performance

First of all, english is not my mother language but ill try my best.

I bought an Acer Predator i17, the graphic chip is a Nvidia gforce GTM980, the Laptop is now roughtly a week old.

i could play Smite, Warframe, Cities Skyline and many more games at max graphic settings, 4k resolution and 60 fps. Somehow now it dropped rapidly, I had to set resolution to 1920:1080 and medium graphic settings on Smite to get between 30 and 40 fps. the only thing I did between those two settings was installing Space engineer, see it crash 3 times on playing Lan, play it local (went fine but low fps) and then deinstalling it. I restarted the Laptop multiple times and nothing changed.

If you need any further Information i will try to provide them, if no solution is found ill send the Laptop in for repairs but after one week that seems a bit special.

(There is no water or other damage, ventilation sounds okay, i ensured a good power supply, core and ram Temperature is okay, no part of the laptop seems to be hot, and startup, shut down happen at the same speed as before, and both hard drives aren't over encumbered (ssd 92gb free hdd 900gb free)

If anyone has ideas what i could test/do i would appreciate it.

thanks in advance