Hi Psicosis,
The only "perfect" solution at the moment is to force the monitor detection by adding 75 ohms resistors to your VGA cable. You need 3 resistors, one for each R, G, B line, connecting the color line to its respective ground.
I know this is not the most appealing thing but it's the only one that works. Maybe the drivers could be short-circuited at some point to force the detection by software, but I wouldn't hold my breath.
The detection fails with arcade monitors, specially if they're connected through a JPAC but not sure if this is a determining factor. An arcade monitor with native VGA input should be detected fine (mine is). By the way, the problem is not limited to 4800 cards, I'd say all models are affected.
When the detection fails, you'll notice 2 issues:
- Interlaced modes are missing.
- Anything above 1600x1200 (either height or width) is missing. This affects 2560x super resolutions. However you can use 1600x super resolutions succesfully.
In this situation, you can still use an interlaced mode for the desktop if and only if you uncheck the "Hide modes that this monitor cannot display" option. But games trying to use them will only be able to do so if they're based on DirectDraw. In the case of GM, apart from using DirectDraw you need disable the "lock_unsupported_modes" option.
By adding the resistors, all the above tricks are not required, and the driver just works as it is supposed to, with D3D and everything.