Indeed, the graphics giant has become so dominant on the AMD side of things that they are able to offer a wide range of supporting chipsets. Currently they offer support to Socket AM2 users with four different chipsets: the nForce 590 SLI, 570 SLI, 570 Ultra and 550. However, the nForce 500 series is now old news as the more up to date nForce 600 series has become available.
Surprisingly, for the first time ever, the latest nForce chipset made its first appearance on the Intel platform, bringing Core 2 owners three new chipsets: the nForce 680i SLI, 650i SLI and 650i Ultra. Nvidia has also released the nForce 680a SLI chipset for the latest AMD platforms, though few have adopted it. Thanks to thriving Intel desktop processor sales, Nvidia had no choice but to turn their attention away from AMD and focus it on Intel.
These two new "for Intel" SLI chipsets focus on performance, and are obviously designed to support dual GeForce cards using SLI technology. Currently motherboards carrying the nForce 680i SLI cost roughly $230, whereas the average 650i SLI board will set you back a more down to earth $140.
We couldn't help but wonder, why does the 680i cost so much more, and can this difference be justified? What are the performance benefits and what new features can you expect to find? Just by looking at Nvidia's website you will quickly learn that the nForce 680i SLI utilizes 46 PCI Express lanes and LinkBoost technology, just like the older nForce 590 SLI chipset.
The fancy named Nvidia LinkBoost technology increases PCI Express and MCP HyperTransport buses by 25%, which in turn pumps the interconnect bandwidth from 8GB/s to 10GB/s. The nForce 680i SLI also includes a total of 46 PCI Express lanes, meaning that both PCI Express x16 slots will operate at full speed when using two graphics cards. This is not a feature offered in the nForce 650i SLI chipset, which is limited to PCI Express x8 speeds when running two cards in SLI.
"Full speed" SLI is nothing new and in fact was introduced back in the nForce4 days, when ASUS released the well regarded A8N32-SLI Deluxe motherboard. Then it became a standard feature for all nForce 590 SLI motherboards, and now all nForce 680i SLI motherboards. While the extra PCI Express lanes are nice, full x16 SLI does nothing to aid the board performance-wise as we have learned from previous tests.
Then there is the more affordable 650i SLI chipset, supporting just 18 PCI Express lanes, it sounds quite poor in comparison, yet this seems to be enough to power dual GeForce 8800 GTX cards. The 650i SLI also misses out on official 1333MHz FSB support, 1200MHz EPP memory support, four instead of six SATA 3 Gb/s ports, and the third PCIe expansion slot for a physics card (right?). Perhaps of lesser importance, the 650i SLI supports a single Gigabit LAN connection versus 680i's dual Gigabit.
For the purposes of our comparison, today the nForce 680i SLI chipset will be represented by the almighty $400 ASUS Striker Extreme motherboard, while in the other side we will have the ASUS P5N-E SLI, a solid offering based on the nForce 650i SLI chipset (our full review of this motherboard can also be read here).