Worse performance and blackscreens after GPU upgrade

I upgraded from a 3070 8GB to a 5080 16GB and have noticed that I get lower FPS in many games now after the GPU swap. After about 30 minutes of gameplay, the computer also usually blackscreens. I have updated both the BIOS and drivers. I have also used DDU to remove leftover drivers. I suspect it might be the PSU being too weak, but I want to double-check here if anyone has had similar problems and maybe knows a solution that doesn’t require a PSU replacement.

System:
CPU: i7 14700KF
Motherboard: ASUS ROG Strix B760-I
RAM: Kingston 32GB DDR5 6000MHz
PSU: Corsair SF750 Platinum