The new chipset is nowhere better than the older one. Moreover, the ASUS A8N32-SLI Deluxe is on average a little slower than the mainboard on the single-chip nForce4 that gives but 8 PCI Express lanes to each graphical slot. So the PCI Express x8 bandwidth is not a bottleneck in today’s applications even if you use extremely high antialiasing levels. Note also that the SLI config on two GeForce 7800 GTX ensures a playable frame rate in Far Cry even at 8x FSAA. This gives you a much higher visuals quality than with traditional 4x FSAA, especially if you also turn on the transparency super-sampling feature.
The A8N32-SLI Deluxe is still a little bit slower than the A8N-SLI Premium on this map, too, although the difference is never bigger than 3 frames per second. As for the absolute level of performance, it seems you can even turn on 16x FSAA in 1280x1024 resolution, but the speed reserve is going to be rather low – it may bottom out to below playable in the hardest scenes.