Many VGA-capable monitors had a 9-pin connector back then. This was common for multisync and b/w monitors.

There's no way to connect a EGA monitor to a VGA card. It's completely incompatible.

I know vga and ega are different, I was kind of hoping that 9pin connector was something more 🤣 kinda weird they didn't use a 15->9pin adapter and resorted to add a 2nd port but stranger things have happened... thanks for the info !

Or they limit you to the older ega/cga ttl standards if the 9pin connector is used?

That's the reason.
The 9 pin connector VGA cards contend for the "best cga emulator" title:
CGA Compatibility Tester vs. VGA cards

CGA emulation has nothing to do with it. Don't mix software and hardware features.

derSammler wrote:

CGA emulation has nothing to do with it. Don't mix software and hardware features.

It does actually.
Original IBM VGA is not fully register-compatible with CGA, and it runs the 320x200 mode at 70 Hz instead of 60 Hz.
This makes some games not work properly, and games will just appear in the standard black, cyan, magenta, white palette, because the palette register does not work. It basically only has BIOS-level compatibility with CGA, and even that is limited.

Some VGA clones have a special CGA mode, which you can generally enable with some software tool. This makes them register-compatible, giving you the correct colours. But when connected to a VGA monitor, you're still faced with the 70 Hz issue.

VGA cards that can connect to a 9-pin RGBI CGA/EGA monitor, can do 60 Hz, and therefore could theoretically give 100% compatible CGA mode.