You can disable Intel’s CA810 graphic adapter by removing the symlink i810 in: /boot/beos/system/add-ons/kernel/drivers/dev/graphics
If your system hangs without this symlink, try to uncomment the line:
bios_calls disabled in your kernel config file.

[Editor’s note: The kernel config file usually resides in /boot/home/config/settings/kernel/drivers although on a fresh R5 install, this may not exist. You will find a suitable template in the sample directory, which you can copy out and edit.]