Close For Voodoo 3 VGA Cards

[quegyboe]

I have a Giga-Byte motherboard and I have a set of dip switches on my board that says "Close for Voodoo 3 VGA cards". I read on a website that a GeForce2 MX will only work on a BX chipset mobo properly if this is enabled and I want to know what it does. Anyone know? I think it raises the AGP voltage but I am not sure...