I’m also running a ZBook G8 with the same issue. The kernel parameter did not fix it.
OS: Arch linux
Kernel: 5.16.14
Nvdia Driver Version: 510.54
GPU: NVIDIA Corporation GA107GLM [RTX A2000 Mobile]
[Wed Mar 16 19:11:27 2022] nvidia 0000:01:00.0: can't change power state from D3cold to D0 (config space inaccessible)
[Wed Mar 16 19:11:27 2022] NVRM: The NVIDIA GPU 0000:01:00.0
NVRM: (PCI ID: 10de:25b8) installed in this system has
NVRM: fallen off the bus and is not responding to commands.
[Wed Mar 16 19:11:27 2022] nvidia: probe of 0000:01:00.0 failed with error -1
[Wed Mar 16 19:11:27 2022] NVRM: The NVIDIA probe routine failed for 1 device(s).
[Wed Mar 16 19:11:27 2022] NVRM: None of the NVIDIA devices were initialized.