Some of the S3 Graphics ProSavage are PCI cards, some are AGP.
Can you tell us if the first slotl, closest to the cpu, is brown and set back closer to the center of the board than the other slots? That should be where your video card is plugged in now... (unless you have on-board video).
Can you give us the numbers off the center area of the board, or the number off the largest chip?
Or better yet, download and run the Belarc Advisor (
www.belarc.com) When you install and run it, it will inventory your machine and give you an opportunity to make a print out of all the contents... It is free, fast, and does not take many resources.
It does appear you can use an 8X card... we could tell for sure if you posted all the info off the old AGP card.
The S3 was actually a decent card when new. Give us the info off that card.