Mac Pro 1,1 Linux Boot Issue

Booting a Linux distribution generates the following: > error: no sultable video mode found. > Booting in blind mode Configuration: - Mac Pro 1,1 Late 2006 - Apple ATI Radeon HD 5870 - DVD drive works - 6 GB RAM Booting from USB Mint: Linux Mint 22 Xfce 64 bit The GRUB script is the default:

setparams 'Start Linux Mint 22 Xfce 64-bit'

    set gfxpayload-keep
    linux        /casper/vmlinuz boot=casper username=mint hostname=mi\  
nt iso-scan/filename=${iso_path} quit splash  
    initrd        /casper/initrd.lz

I have seen suggestions to change splash to nosplash and add debug nomodeset Also consulted Matt Gadient's excellent website. I have tried various other distributions and versions: Ubuntu, Arch and most of those do not show an EFI from the Mac boot device selection. Nothing seems to work although many people have reported success with this configuration. Can anyone suggest a fix?