This is an intersting find Osckhar, it seems that there were quite a few of thes 5000's made, I wonder how many?
your model is a Rev.A0 3700 by the looks of it, possibly the latest of it's kind, but id we get the 5000 PCI it's design is alot older, they are reved and dated with Rev.A1 0900, this must be also the reason why 3dfx changed the model layout of the 5000 PCI to the AGP layout, smaller and there fore maybe easier to fit is other cases.
here the Voodoo5 5000 PCI 32MB Rev.A1 0900 from Edmundoab:
and here the Voodoo5 5000 AGP 32MB Rev.A0 3700 from Osckhar
as you can see the difference if rather big.
If anyone really knows why 3dfx changed they layout so differntly, would be nice to know.