On the box, the slowest processor listed is the AMD K6 processor. Isn't that AMD's Pentium-class processor?
The old Matrox card was also PCI.
My other 2 PCs use AGP and PCI Express for the video cards. They do have PCI slots--BUT they don't seem to work well with PCI video cards. The screen goes blank after Windows finishes loading.
The cardbus connector looks like the Universal 32-bit PCI Card in the Wiki pic. The PSU is 11 yrs old, but it is 300 Watts--more than stated minimum of 250.
It starts up normally when I put the Matrox back in.