I found this Link, which seems quite good :
http://www.ertyu.org/~steven_nikkel/agpcompatibility.htmlAccording to it, the AGP Pro Slot comes in 2 Versions, keyed for 3.3V support, and one Keyed for 1.5V support.
Generally :
- AGP Pro slot was a workaround to allow for more power to AGP Cards
- was seldomly used however (nowadays, Cards take additional Power Connectors directly from the Power Supply instead)
- was generally noted to be
not compatible
with older 3.3V AGP Cards
(as it was future oriented, I assume most were built with the 1.5V 4xAGP variant in mind, never actually heard of or seen a 3.3V variant myself)
So it looks like the A7V133-C is a special case,
not supporting a Voodoo5.
ASUS description reads : "AGP Pro/4X"
(I'll therefor have to correct/edit my above posting)