I've added strings with EFI studio, which gives me the same result as nvinject.

I booted again from the iatkos disk and installed the nvenabler.kext from it. Starting up with normal boot gives me a blue screen on both monitors, where the desktop hasn't loaded, but there aren't any graphical artifacts either. Added device ID (0x06e410de) to nvenabler, and I will look into the blue screen thing later and see if I can find any way past that. Safe boot just gives me the default vesa screen again with no resolution shifts, and only one screen.

Thank you again for your help here
Does anything come to mind right off that would cause these sorts of artifacts?