Dreamcast with VGA and RGB.

[aldair]

With VGA and RGB plug PLUS OSSC any monitor or TV will work 15kz(rgb) and 31kz(vga).

[KnightNZ]

Any more details? Does this effectively turn the DSub connector into operating in the same mode as a scart connector?

[aldair]

Any more details? Does this effectively turn the DSub connector into operating in the same mode as a scart connector?

All I had to do was use a switch to turn it on:
Pin 7 to gnd-RGB.
6 and 7 on GND is VGA.