allready found on what would of been placed on those connectors St4r4m4m4? I still think it maybe used for a Stereo In, for ASUS's 3D Shutter glasses:
http://www.tweakers.com.au/articles/graphics/asusgf3ti200/glasses.jpg

just look at the connector next to the VGA-out:


here a GeForce2 GTS Deluxe from ASUS , if you look carefully on the far left of the bracket you can see a very small round black connector aka the VR out put [Virtual Reallity output]


here some more detailed pics of that ASUS GeForce2 GTS with that VR Output:

Top, look at the top black connector:

Bottom:

I've updated my Post, with better and clearer shots on what I mean I used shots taken from an ASUS V8200 GeForce3 Deluxe card to get the better idea.

on this later model GeForce3 Deluxe the VR-Out put can be seen also:


it's indeed the same type of small hole on you Voodoo-Rush's Backplate and it's placed at the same height as your is, so I think that your strange hole was meant for a VR output

Here shown how the VR is placed in that small out put like hole just to get my idea of the whole thing :