Andrew,
I have identical CPU and GPU (and similar SSD) specs as what you have. I’m following this thread in case there’s an obvious solution to a crashing Pix4D 4.3.31 (as I’m experiencing the same thing).
In case it helps: I had success running projects via the command line interface in Pix4D 4.2.27 for projects that would otherwise crash Pix4D when run via the desktop GUI. The command line interface isn’t available in Pix4D 4.3.31, so one thing I might try is to roll back the Pix4D version that I’m using and try the CLI instead…
Here are some of the details of how I came to the CLI solution: https://community.pix4d.com/t/7060–Desktop-Pix4Dmapper-4-2-27-slow-step-3-processing-with-full-CPU-usage-
Good luck!