Problem with a new 5090

Bought a Zotac Solid OC 5090 few days ago (pretty much the only 5090 available here). Replaced it with my old Nvidia GPU and updated the driver. Everything seemed fine, but then I noticed that every hour or so the screen flashes black for a brief second and my driver settings get reset. Once my entire system just decided to reboot itself during the black flash. I made sure the GPU is properly mounted in its place and checked that the cable is properly secured to the GPU. I decided to reinstall windows from scratch and just have a clean install in case the old drivers are causing issues. But today I again experienced the black flash and the driver settings were reset. Now I'm thinking either my PSU doesn't have enough juice or the GPU is faulty.

I have EVGA Gold 1000W PSU. My CPU is Ryzen 7 9800X3D, 32GB of DDR5 RAM and 3x M.2 2TB SSD.

Should I buy a bigger PSU and try it out if that fixes the problem or does someone know if this just means the GPU is faulty?

I'm just looking for some opinions or if anyone has experienced something like this before.