You ask how we survived the year 2000. Honestly by that point, if you bought a system to play games then, you were buying Athlon or P3. Socket 7 was around but it was the very low end and was at the point of being phased out. I had bought my K6-3 a year earlier, and I think I ran a voodoo 2 on it. Some people I knew had banshee in AGP form, which was a cheaper solution then too. In '99 some people had voodoo 3 or TNT2 if they had money to spend. Like I said, by 2000, we were starting to look past socket 7.
I looked at the pictures of the board you linked to, and the AGP slot looks like 3.3V. So that means AGP 2X max. And with the socket 7 technology probably early AGP anyway. The cards you have been trying are 4X or even 8X, and a 1-4 years newer than your socket 7 class system. While there was backwards compatibility to 2X, it was very spotty in those days, and might not be very good with your socket 7. Generally speaking, when I built a system at the time, I would have looked over the bus specs, and pick cards that matched it. I would have been pretty nervous to spend money on an expensive AGP 4X card and not have it work in socket 7 at the time.