nForce4 SLI X16 interconnect bandwidth tested
PC Perspective has an interesting article
investigating ATI's claim that limited interconnect bandwidth will hinder the performance of PCI Express graphics cards connected to the south bridge on NVIDIA's nForce4 SLI X16 chipset. ATI claims that there isn't enough real interconnect bandwidth to satisfy a 16-lane PCI Express link, especially with south bridge I/O traffic thrown into the mix. The article tries this claim by testing how HT bandwidth and I/O load affect the performance of graphics cards connected to the south bridge. As it turns out, even artificially reduced HT bandwidth and high storage and network I/O traffic have only a marginal impact on graphics performance. ATI's Radeon Xpress 3200, which consolidates all its PCI Express lanes on the north bridge, may be a more elegant solution than the nForce4 SLI X16. However, the X16 appears to have plenty of interconnect bandwidth for south bridge-connected graphics cards.