nVidia's new nForce 4 SLI X16 chipset
The nForce 4 SLI X16 is the normal SLI chipset on steroids - we think that's the best way to explain it. As with the regular chipset, when we want to SLI our graphics cards, each PCI Express graphics slot is given 8 lanes of bandwidth. The X16 variant of the nForce 4 SLI gives us two full speed 16 lane PCI Express slots making sure that we get the most potential for our current nVidia graphics cards which come with PCI Express 16x capable GPU's.
18 PCI Express lanes are added to the new AMD version of the chipset providing a total of 38 PCI Express lanes (40 on the Intel platform). 32 of those lanes are used for the graphics cards, the remaining lanes will be setup differently depending what the motherboard manufacturer wants to do with them.
On the AMD platform, the extra PCI Express lanes are made available thanks to the addition of the new System Platform Processor (SPP) that is connected via the Hyper Transport Link. The Hyper Transport offers us a maximum bandwidth of 8GB/s and shouldn't cause any latency problems with the SPP coming between the CPU and the MCP.
Apart from the extra PCI Express lanes, the difference between the current SLI chipset and the new seems minimal. No pricing is currently released on the motherboard so it is hard to tell if the X16 will phase out the other SLI chipset as one would assume if pricing is similar you would venture for the newer X16 variant, as more is always better - especially for future-proofing your motherboard.
ASUS are currently the only motherboard manufacturer that we have heard of with a motherboard ready to come out utilizing the new chipset and it would seem they are getting the jump on a lot of their competitors much like they did when we saw the release of the original nForce 4 SLI chipset.