Voodoo 1 and 2 were simple analog VGA pass-thru, they'd take over the VGA output when in use. I don't think the VGA input was even wired to anything other than

Voodoo 1 and 2 were simple analog VGA pass-thru, they'd take over the VGA output when in use. I don't think the VGA input was even wired to anything other than the pass-thru switch, you may be thinking of something else. There was no such conversion.