Nvidia nForce 600i Chipset: Half-New
Nvidia usually releases more than one chipset modification. The same is true for the 6th nForce series: they used the same MCP and SPP chips with slightly different sets of supported features to build three products targeted for different price groups. The top-of-the-line solution is nForce 680i SLI, the mainstream chipset is called nForce 650i SLI, and the value chipset in the family will be called nForce 650i Ultra. By artificially disabling some of the nForce 680i SLI features and reducing the number of supported PCI Express lanes they will create better value chipset modifications from the top nForce 680i SLI solution, therefore we will devote our today抯 article to this particular product in the first place, because this way we will get a good idea of all three newcomers.
Although Nvidia nForce 680i SLI is a pretty advanced product, which features look very impressive even against the background of competitor solutions, our today抯 story will not be too long. Like Nvidia nForce 590 SLI for Athlon 64 processor family, the new nForce 680i SLI chipset consists of two chips: SPP and MCP connected with HyperTransport bus. The MCP of this chipset is am MCP55PXE chip that you should know very well from the previous materials devoted to Nvidia抯 chipset solutions. In fact, this MCP serves as single-chip nForce 570 SLI core logic for AMD platforms. The new Nvidia nForce 680i SLI has an additional SPP chip connected to it via the HyperTransport bus, and not the processor. It features a number of integrated controllers, supports Quad Pumped Bus and additional PCI Express lanes.
MCP analogs from the Nvidia nForce 680i SLI chipset have already been used in other Nvidia products, such as nForce 590 SLI for AMD and Intel systems, for instance. So, we have already discussed most of the features implemented in the new Nvidia chipsets before, so for more information please see our article called Chipsets for Socket AM2 Platform: ATI CrossFire Xpress 3200 and Nvidia nForce 590 SLI.
The most interesting part of the new Nvidia nForce 680i SLI chipset is certainly the chipset North Bridge (SPP). Nvidia hope that this microchip will help them compete successfully with the Intel抯 own chipsets from the performance as well as overclocking prospective.
As you know, the previous Nvidia solutions for Intel platform (based on the old C19 SPP) couldn抰 boast any significant overclocking potential. The increase in FSB frequency above the nominal rate would very soon lead to loss of system stability. The new C55 SPP officially supports 1333MHz bus that will be used by upcoming dual-core and quad-core processors on Core microarchitecture. And it means that Nvidia nForce 680i SLI boasts higher frequency potential.
The memory controller has also undergone pretty significant changes. Nvidia nForce 680i SLI has officially acquired DDR2-800 SDRAM support that the previous chipset solutions for Intel platform didn抰 have. However, in reality, the new SPP features a greater choice of dividers forming the memory bus frequency from the FSB speed, so that you will be able to increase the memory speed up to 1200MHz in the nominal mode. Moreover, the new SPP boasts very well implemented mechanism for asynchronous memory bus clocking. As a result, Nvidia nForce 680i SLI may have the DDR2 SDRAM working at frequencies that are not connected with the FSB speed and can vary in a very broad range. Some overclocking fans may also be happy about the asynchronous memory clocking. Although the performance of the DDR2 memory controller gets slightly lower in case of asynchronous memory clocking, it allows setting the memory frequency lower than the front side bus frequency. As a result, you can use low-cost memory modules with limited overclocking potential in overclocked platforms on Intel Core 2 Duo and Core 2 Quad processors.
Note that Nvidia engineers paid special attention not only to the flexibility of the integrated memory controller of their nForce 680i SLI, but also to its performance. The SPP of the new chipset features enhanced DASP 4.0 unit (Dynamic Adaptive Speculative Preprocessor) responsible for pre-opening of those memory pages that might be later requested by the CPU. Together with the data prefetch algorithms implemented in contemporary Core based processors this technology may ensure additional performance improvement in applications working with large amounts of data.
The second important advantage of the Nvidia nForce 680i SLI memory controller is its ability work at 1T Command Rate. Mainboards built around this chipset will offer a corresponding option in the BIOS Setup. Note that competitor抯 solutions, the Intel chipsets in the first place, work only with 2T Command Rate and do not allow adjusting this parameter. This gives us another reason to believe that the new chipsets will demonstrate higher performance.
Also the memory controller of Nvidia nForce 680i SLI supports overclocker抯 DDR2 SDRAM modules with EPP (Enhanced Performance Profile), which allows setting automatically optimal memory work modes for memory kits with EPP support, that are getting more and more popular these days.