How did I know?
NO IT IS NOT POSSIBLE TO SLI WITH THE PCI BUS.
The cards say this because they are native PCIe cards, and their native PCIe equivilants ARE SLI capable. But the PCI bus is NOT capable of handling even one of those cards properly...let alone two in SLI.
That's like saying, well I've got 5 PCI slots, so I'll go Penta-SLI!!!! It just doesn't work that way.
Voodoo2 cards ran on the PCI bus and were the first SLi capable cards.
Perhaps Legendary should trawl ebay and pick up a couple of 12mb Voodoo 2's.
As for modern cards on a PCI bus then no