NVIDIA has been quiet about core logic since nForce4 x16 was launched a few months ago, but the company is rapidly approaching on final silicon for the MCP55 family.  MCP55, as we reported previously, is the nForce4 successor dedicated to Socket AM2/S1 motherboards.  Our sources in Taiwan have just confirmed with us that MCP55 spin A02 is available to manufacturers and is already implemented on working motherboards.  The A01 spin has been floating around on engineering samples since January.  Traditionally, A02 and A03 spins end up in the market place on retail motherboards.

Unfortunately, MCP55 is a far cry from a revolutionary chipset.  According to NVIDIA roadmaps, it contains a different audio codec, dual Gigabit Ethernet PHYs and can use six SATA channels instead of four, but the core logic is still hampered by the fact that it takes two chipsets to control a 2x16 SLI setup.  The majority of games today cannot take complete advantage of 2x16 SLI yet, but adding two Northbridges to the motherboard to enable 2x16 seems like an incredible waste of money (particularly when the interconnect between the two bridges is only exactly enough for than the actual x16 PCIe bus, even though there are other devices on the controller). 

ATI's still unreleased Xpress 3200 (RD580) core logic can support 36 PCIe lanes on the Northbridge.  Recent roadmaps revealed that a stripped down version of RD580, RD550, will compete directly with MCP55P with 2x8 PCIe lanes rather than a full 2x16 for multiple GPU support.