First of all, we have to make very clear that although today's chipsets support varying features and target different user segments, you won't notice any difference in performance between a motherboard using a P965, 975X or nForce 680i SLI chipset when you start Windows to attend to your daily business. Only if you belong to the feature-aware, performance-hungry or overclocking-savvy crowds will you appreciate the huge overclocking margins and plethora of tweaking options.
Intel's P965 and 975X chipsets represent the establishment, both because most Intel-based systems are powered by Intel's very own chipsets, and because Intel processors have traditionally run best with an Intel chipset. Although the 975X has been available for over a year, it is still the high-end product - it is paired with the ICH7 southbridge, and thus offers a nice range of interface options. However, the P965 is the latest core logic product, utilizing the ICH8 southbridge family with even more goodies. There is a large variety of 965 and 975 motherboards available today.
Nvidia has been in the chipset arena since 2001. Although its first nForce chipset failed, the nForce2 and following generations were increasingly successful. Today, the nForce 4 and 5 series are considered among the best choices for Athlon 64 solutions, and Nvidia is hoping that the nForce 6 will give it a big share of the Intel market. It is the larger business space, but also more difficult to get into: Nvidia already tried its luck with the nForce 4 Intel Edition, but even though the product was great, it couldn't take significant market share from Intel.
The nForce 6 chipset is supposed to be better than the Intel chipsets in every way: better overclocking, better storage subsystem, better dual x16 PCI Express SLI graphics as opposed to Intel's dual x8 PCI Express Crossfire support, better networking support and better memory auto-configuration. Let's dig into this new chipset and find out if it delivers.