I would start troubleshooting by downloading the Dell OEM WHQL RTX driver from the XPS 8950 drivers page, 31.0.15.1694, A01. Save it to your Windows desktop. Uninstall the retail Nvidia driver. Install our OEM WHQL RTX driver. Reboot when done and retest. By the way, the purchased 1 year warranty expires in December. If you want to extend the warranty =* Go here* Enter the private Service Tag* Under, "Support Services" at top, click "Extend or Upgrade"
On my XPS 8950, the resolution decreases when I exit the screen "sleep" mode, i.e., Settings > System > Power > Screen and sleep > When plugged in, turn off my screen after > [x minutes] What is happening is Windows 11 and Nvidia "forgets" the model of monitor and its resolution. So, the system defaults to a lower resolution. Restarting the computer doesn't fix it. I have to reinstall the monitor's *.inf file so the system knows the monitor and its resolution. I can then restore the native resolution using the Nvidia Control Panel or Windows Display Settings. How do I stop the resolution from changing when I "wake up" the screen?
XPS 8950, exiting sleep mode, resolution changes?