The highly anticipated NVIDIA nForce4 chipset was officially announced at around the same timing as of the AMD Athlon FX-55 and 4000+ therefore it can be viewed as a joint marketing effort by the two chip companies. NVIDIA nForce 4 is the second PCI Express chipset for AMD platform finally due for release on Oct 20th, about one month later than the VIA K8T890 chipset. nForce 4 comes with 3 different variants targeted at different market segments. The top end model touted the nForce 4 SLI sports exciting features such as 20 lanes of PCI-E that makes SLI technology possible for dual graphics cards capability as well as the SATA 3GB/s support. Also networking security feature is greatly enhanced with NVIDIA Active Armor with Firewall 2.0. Specially for performance enthusiasts, NVIDIA has also created nTune software to provide numerous tweaking functions to optimize system performance within Windows environment. Indeed, the absence of Sound Storm 2 feature in nForce4 is a pity and the decision to drop it is due to cost in order to be better positioned against lower priced VIA and SiS chipsets. In this article, we will look in details the features of the nForce4 and how it paired up with the FX-55 to maintain performance leadership in the AMD chipset arena.