NVIDIA 780i: Evolution Plus Triple SLI

nForce 780i Platform

NVIDIA targets their top chipset at the "hard-core overclocker", and each new generation adds more features that cater to the computer enthusiast. The nForce 780i tops the product line and defines state-of-the-art for NVIDIA chipsets.

The 780i is the 680i chipset with an added nForce 200 chip to support 32 lanes of PCIe 2.0 capabilities. This allows the addition of 3-way PCIe with three x16 PCIe slots. It is important to point out that while there are three x16 slots for 3-way SLI, only two of the x16 slots are PCIe 2.0 compliant. The third x16 slot is derived from the nForce 570 MCP (identified in the block diagram as the 780i SLI MCP), which is an older chip that is not PCIe 2.0 compliant.

The nForce 200 is a PCI Express switch chip with one upstream port and up to four downstream ports. The 780i provides two x16 PCIe 2.0 downstream ports, which can also be configured as four x8 PCI Express 2.0 ports. The interface between the 200 chip and the 780i SLI SPP provides a maximum bandwidth of 4.5 GT/s per link, which is enough bandwidth to provide full performance of PCI Express 2.0 Graphics cards like the 8800GT.

In the launch review for the 680i chipset we saw the 680i with a total of 46 PCIe lanes, distributed as 18 with the SPP and 28 with the MCP. As you can see in the above diagram 780i has 62 PCIe lanes, distributed as the same 28 lanes on the MCP, just two lanes on the SPP, and 32 PCIe 2.0 lanes on the nForce 200 chip. The extra 16 PCIe lanes on the 680i SPP provide communication with the nForce 200 chip. The bottom line is the 780i picks up an extra "full" x16 PCIe slot. The PCIe lane count, ports, and device support are otherwise the same as the 680i chipset.

With the addition of 3-way SLI as a new 780i chipset feature, NVIDIA believes hard-core gamers and performance enthusiasts will migrate to the 780i motherboards. We will examine Triple SLI performance in a separate review that you will definitely want to read, particularly if you are a hard-core gamer.