NForce2 - Development

Development

The nForce2 features two different southbridges, the MCP and the MCP-T. The two differ only in audio and Ethernet integration. The latter is equipped with two 100 Mbit Ethernet NICs (nV and 3Com 3C905) and the impressive NVAPU (SoundStorm) with hardware accelerated 3D audio and real-time 5.1-channel Dolby Digital encoding whereas the first features one 100 Mbit NIC and an AC'97 audio controller. For audio, both MCP units were connected to an external codec chip, such as a Realtek ALC650. With the MCP, this codec provided all software-driven audio duties, while with the MCP-T it performed the DAC duties. Unfortunately, the external codec and unavoidably noisy motherboard circuitry (EMI/RFI) were detrimental to audio quality on even the MCP-T equipped boards, and as a result the nForce audio solutions were never of high fidelity unless the S/PDIF output (TOSLINK or coaxial) was used.

The nForce2 chipset was remarkable for its advanced memory controller. It introduced a dual-channel memory interface to the mainstream market, doubling theoretical bandwidth. This was deemed necessary for the nForce2 IGP, with its GeForce4 MX-class integrated graphics, to be performance competitive budget solution. It was also important not to divert bandwidth, by sharing memory bandwidth with the most powerful IGP produced for Socket A, from the rest of the system. The Athlon's EV6 system bus was incapable of saturating the second channel, as this bus between the CPU and the north bridge was limited to the Athlon, AthlonXP, Duron, and early Sempron design to use a single 64 bit DDR channel. As a result, the second 64bit memory channel between the north bridge and the memory was almost exclusively available for the GPU. In dual-channel configurations of the nForce2 without IGP, the Athlon XP only showed gains of 5% at most in memory bandwidth intensive applications. Comparatively, in dual-channel configurations with IGP graphics, performance was demonstrably equivalent to dedicated GeForce 2 MX cards employing 64bit DDR memory or 128bit SDR memory.

Among various fixes and refinements compared to the original nForce, nForce2 featured a fixed PCI/AGP clock, i.e. PCI and AGP frequencies will not change when changing the FSB. As a result, the nForce2 platform was known for its ease in overclocking AMD processors, and was a favorite for years with the overclocking community. It was also known that the chipset gave best performance with FSB and memory running synchronized, asynchronous operation delivered an unusual high performance loss.