Another build that I did, wich was just too fast for Win98-Gaming, was this little baby here.
It skipped frames ahead instead of the usual lagging. (Kind of lagging turned upside down)

I did benchmarking with both my Radeon9600 (SE/LE-Whatever), and my Medion Radeon9800-XXL.
The numbers tell me nothing about why it is too fast on the 9800 card.
It was better balanced with that 9600 instead. (GF4 would not run good on this build)

It was an MSI K8MM-V board with an Sempron-3300+ (2ghz model)
512mb of Ram and an YMF-724 card. Great and simply too fast stuff for Win98se. (for me at least)