For AMD platforms, the nForce 590 SLI SPP (what was commonly known as the “northbridge”), supports a single x16 PCIe connection as well as 2 x1 connections. All products that are branded nForce 590 SLI, include both an nForce SPP and nForce MCP (this two chip solution is commonly referred to as a “chipset”). Because this is a dual X16 PCIe platform, it has to be paired with a media and communications processor (MCP), or what is commonly referred to as a “southbridge.” The MCP chip used in this solution is called the nForce 590 SLI MCP. The nForce 590 SLI MCP incorporates the second x16 PCIe as well as 4 x1 connections.
Because AMD incorporates a memory controller into its CPUs, we can also utilize the nForce 590 SLI MCP as an alternative single chip solution that provides a dual x8 functionality for more mainstream PCs. For these specifics uses, the nForce 590 SLI MCP is used but is branded to consumers under the nForce 570 SLI name. This is necessary so that consumers can distinguish between the nForce 590 SLI solution which is dual x16, and the nForce 570 SLI solution which is dual x8.
For Intel, we have a nForce 590 SLI Intel Edition SPP that also incorporates a memory controller for Intel CPUs. This SPP is paired with the nForce 590 SLI MCP, which is the same thing as the nForce 570 SLI MCP. Some programs, including CPU-Z, report the “southbridge” as nForce 570 SLI MCP. This is fine. However, you need to distinguish between what NVIDIA brands as the nForce 590 SLI solution vs. the individual chips which are used on the motherboard.
For the XPS 700 and 710, Dell uses the nForce 590 SLI SPP (for Intel) “northbridge” and the correct southbridge, which in this case, is the nForce 590 SLI MCP, also known as the nForce 570 SLI MCP. Dell’s implementation is the one represented in the first two pages of this PDF on our site that some of you referenced in the comment thread to Lionel’s earlier post on this topic.