Im running on Gigabyte 2080Ti OC with 32GB 3000MHz memory. And my FPS varies between 40 and 50.
Nvidia driver version - 457.30. My GPU is manually overclocked with core clock raised by 100MHz and GPU memory by 1000Mhz.
Temperature while running Cyberpunk on 1440p on Ultra is around 65-70c with GPU fans on 45-50% spin.
First thing first. I would suggest you to run HW Monitor in background while you play the game and keep an eye from time to time on GPU temps.
Those shut downs sound more like GPU is thermal throttling and shutting down to prevent damage to GPU.
I dont say this is the case with your GPU, but you need to eliminate hardware issue first in order to try to mess with software next.
If thats the case, just reduce your ingame graphic settings and that should fix the issue.
Next. You can try updating your drivers.
I always tell people to use Direct Driver Uninstaller for removing GPU drivers.
Tho its a extra step, its most secured that you removed ALL traces of previous drivers.
And always use "clean" drivers. Those drivers are strip down of all Nvidia bloatware and left with all necessary files to use GPU fully.
I usually download mine from here -
https://forums.guru3d.com/threads/46...ersion.433367/
hope that this helps a little.