I have some old HP DL380 G6 servers, and I started having a problem after 7.2 where when I clicked on 'Install Proxmox VE' at the first menu, the screen would go blank. I was hoping that this problem would go away with version 8.0, but it still persists. My solution was to select 'Advanced Options' at the first menu, and then select 'Install Proxmox VE (Console Mode - nomodeset)'. After this you can follow the prompts to install the system without a problem.