Hi,
About the rig 1 :
With a Voodoo 3, i would go for Win9x.
You say that (I quote you) "Some (not so old) games give me some errors or won´t start".
What game ?
The card is 16 Mb memory and 16 bit color rendering limited so it can't run any "modern" game.
With XP, i would go for a Voodoo 5.

About the rig 2 :
Win9x would be better because of its Dos mode and pierrickuk explained very well : "early glide games will be very happy with your voodoo1, especially under DOS".
Voodoo 2 (Sli if possible) would be a better choice for "modern" Glide games.

Hi,
My Sli setup runs with a K6-3

Hi,
The 102_Omega_Special ? indeed it was known for running Colin McRae Rally 2 without locking up the computer.

I would unistall again driver and 3dfx tools.
Then i would use this utility driver cleaner and install again driver / 3dfx tools

ps : backup your registry before

Hi,
The best is you buy a new gfx card.

Hi,
It was a Pentium 233 MMX (fsb 66)

Hi,
Go here please, use the utility pci.exe as explained by Hank.

We need to know if the card is alive or dead.

Hi,
If you disable Vsync, how is the performance ?

Since you're running a K6, in your BIOS look for an entry with something like Write Allocation or Write Enable and enable it.

Hi Obi,
I received my V5 5500 A2 today.
(rottentreats was not the seller).
This is the same like your's.

Hi,
Did you try MesaFx ?
https://www.3dfxzone.it/dir/3dfx/mesafx/index.php

Why a Voodoo3 PCI ? they are expensive and not easy to find
It's easier to find some Voodoo3 Agp ?

Hi,
Did you try to mod a V3 ?

What's the system requirement ?
Probably, it is not any more a DX6 game

Is your card listed twice in the device manager tab of the system properties ?

Hi,
Can you do a ctrl-alt-del in order to see what is running ?

Hi,
Was an other 3dfx card previously installed in your system ?
What is the  error message ?