Cheers for that @darthnVader. While I understand there is a pixel clock limitation, something isn't adding up. When I received my Mac Mini G4s from eBay, they were running Mac OS X 10.4.11 and worked on my BenQ 27" monitor 1920x1080@60 straight out of the box. For fun I reinstalled Mac OS Tiger 10.4.1, I hit the fuzzy graphics/out of range issue. It wasn't until it patched all the way to 10.4.11 everything came good.
My psychic debugging tells me that Apple put something into Mac OS X 10.4.11 to deal with the pixel clock issue.
In your post there is a quote regarding SwitchResX, is there something I can do with that tool that can propagate the resolution/timings into Mac OS 9 or am I basically stuck with what I have at the time being?
The Pixel clock limit can be a real issue, compounded by the fact that most displays don't state if they are coherent/non-coherent.
I had to use the 'NDRV' from 10.3.7 for the Mini, as later 'NDRV's were not compatible with OS 9, and OS 9 'NDRV's are not compatible with 10.4.x and later. Apple changed the ways 'NDRV's work, and didn't care about OS 9 compatibility.
So check if the display works correct in 10.3.7 on the Mini @1080P, if it doesn't, then you're not going to have a whole lot of success with it in OS 9.
Apple's documentation on 'NDRV's is next to useless, and only the people that wrote the 'NDRV' for Qemu's VGA can really help us, and I don't know who that was to ask, but I've never asked at the qemu-ppc mailing list.