Ubuntu 20.04 P600 keeps falling off the bus

Hello everyone,

I have changed from Windows to Ubuntu recently on my laptop (HP ZBook 15v G5) and as of last week only used the Laptop in combination with a Zotac Amp Box Mini + GTX 1060. This all works great.
Now I have tried to use the laptop without an external GPU and I keep getting random freezes about ever 30 min to 2 hours thus rendering the laptop basically useless.

I am currently running the 455.23.04 driver however I have also tried the 450 and 390 version. Furthermore I have tried to disable the processor power modes, updated the BIOS and switching to lightdm. Also I have completely removed the NVidia drivers and reinstalled them several times.
All of this did not make any difference to the frequency of the crashes however if I run a stress test it did not freeze up over 3h of runtime.
Running on the internal screen, one or two external screens also does not matter.
To see if the crashes happen during a power state I had nvidia-smi running. As far I could tell the crashes always seem to occur during the P5 mode.

I am really lost right now and do not know what else to try. As I am new to the Linux world I just do not know what else to do. I have attached the latest crash report but please feel free to ask for anything else you might need.

Best regard
nvidia-bug-report.log.gz (368.1 KB)