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Nvidia's nForce 680i SLI chipset

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FOR MONTHS, ENTHUSIASTS WAITED for a version of Nvidia's high-end nForce 590 SLI chipset compatible with Intel's Core 2 processors. That chipset finally arrived in October aboard Asus's P5N32-SLI Premium motherboard, but not before Nvidia hinted that a new nForce 680i SLI was just around the corner. Now, less than a month later, we've turned that corner to find the 680i SLI riding a motherboard built by Nvidia itself.

Chipset manufacturers usually produce a reference motherboard design to help their partners bring products to market. When the nForce 590 SLI chipset launched for Socket AM2, Nvidia worked with Foxconn to make its reference design a retail board. This time, Nvidia has taken things one step farther, designing and manufacturing its own nForce 680i SLI motherboards for sale to its partners. Some of those partners, including Biostar, BFG Tech, ECS, EVGA, and XFX, have been so impressed with the design that they'll be offering it as-is.

Of course, there's more to the nForce 680i SLI than Nvidia's swanky new motherboard. The chipset also features a new north bridge chip that's built using 90-nano process technology and features a completely redesigned memory controller. Nvidia has even rolled out an updated version of its nTune system utility for the occasion.

Rather than launching as a standalone chipset, the nForce 680i SLI is coming to market as a complete platform. I really hate to call the 680i a platform—that word is misused in far too many press releases these days—but that's really what it is: a complete platform, including the chipset, motherboard, BIOS, and software, built explicitly for PC enthusiasts. The question, of course, is whether it's the right platform for your next Core 2 Duo build. Read on to find the answer.

A new generation?
Before getting started, I suggest thumbing through our latest reviews of Core 2-compatible chipsets. We've already covered the Intel 975X and P965, and the Nvidia nForce4 SLI X16, 570 SLI, and 590 SLI chipsets in great depth, and today our focus will narrow on the nForce 680i SLI.

With a name like nForce 680i SLI, you might expect Nvidia's new chipset to be a generation ahead of the preceding nForce 500 series. You'd be wrong. These days Nvidia is giving out nForce numbers more to differentiate its products than to represent their heritage, ostensibly because nForce chipsets often use north and south bridge chips from different generations. The nForce4 SLI X16, for example, has essentially the same north bridge chip as the nForce 570 SLI and even 590 SLI.

975X Express P965 Express nForce4 SLI X16 SPP nForce 570 SLI SPP nForce 590 SLI SPP nForce 680i SLI SPP
Front-side bus 1066/800MHz 1066/800MHz 1066/800MHz 1066/800MHz 1066/800MHz 1066/800MHz
Memory controller DDR2-667 DDR2-800 DDR2-667 DDR2-667 DDR2-667 DDR2-800
PCI Express lanes 16 16 20 20 20 18
Multi-GPU support CrossFire CrossFire* SLI SLI SLI SLI
Chipset interconnect DMI DMI HyperTransport HyperTransport HyperTransport HyperTransport
Peak interconnect bandwidth 2GB/s 2GB/s 8GB/s 8GB/s 8GB/s 8GB/s

Rather than stretching that chip across another nForce number, Nvidia has rolled out a brand new north bridge for the 680i SLI. This chip is manufactured on a 90-nano node by TSMC, and features a memory controller that Nvidia says has been completely redesigned. Part of that redesign involved reducing latency in the memory controller's Dynamic Adaptive Speculative Pre-Processor (DASP) 4.0 prefetch mechanism, and tuning it for optimal performance with the larger cache sizes found on Core 2 processors.

Unlike Nvidia's previous north bridge chips, the 680i SLI SPP has native support for DDR2-800 memory. Expect to see motherboards provide plenty of options for higher memory bus speeds, including the ability to run synchronously with the 1066MHz front-side bus. That should be a particularly fast configuration, according to Nvidia, because the 680i's Quicksync mechanism allows it to bypass traditional asynchronous mechanisms when running synchronously.

Apart from its process shrink and new memory controller, the 680i SLI SPP looks a lot like its predecessor. The chip retains support for a 1066MHz front-side bus, and the 8GB/s HyperTransport link Nvidia uses as a chipset interconnect. It does have two fewer PCI Express lanes than the nForce 590 SLI SPP, but with 28 PCIe lanes at the south bridge, there are still plenty to go around.

ICH7R ICH8 ICH8R nForce4 SLI X16 MCP nForce 570 SLI MCP nForce 590 SLI MCP nForce 680i SLI MCP
PCI Express lanes 6 6 6 20 0 28 28
Serial ATA ports 4 6 6 4 4 6 6
Peak SATA data rate 300MB/s 300MB/s 300MB/s 300MB/s 300MB/s 300MB/s 300MB/s
Native Command Queuing Y N Y Y Y Y Y
RAID 0/1 Y N Y Y Y Y Y
RAID 0+1/10 Y N Y Y Y Y Y
Matrix RAID Y N Y N N N N
ATA channels 1 0 0 2 2 1 1
Max audio channels 8 8 8 8 8 10 10
Audio standard HDA HDA HDA AC'97 HDA HDA HDA
Ethernet N N N 10/100/1000 10/100/1000 2 x 10/100/1000 2 x 10/100/1000
USB ports 8 10 10 10 8 10 10

At the south bridge, the nForce 680i SLI borrows from the 590 SLI. Seriously. The 680i SLI MCP is identical to the nForce 590 SLI MCP.

Of course, the nForce 590 SLI MCP isn't exactly hurting for an upgrade; with six Serial ATA RAID ports, dual Gigabit Ethernet controllers, 10 USB ports, support for "Azalia" High Definition Audio, and an ATA channel for good measure, it's easily the most feature-rich south bridge chip around. About the only things missing from the MCP are support for AHCI and Matrix RAID. The former provides a framework for Native Command Queuing (NCQ) implementations and requires a license from Intel, but since Nvidia has its own NCQ implementation, AHCI isn't a necessity. Something akin to Matrix RAID would be nice, though, if only for the ability to combine RAID 0 and 1 partitions using only two hard drives.

Even without AHCI and Matrix RAID, the nForce 680i SLI provides a few extra perks that its competitors do not, including hardware TCP/IP offloads for both integrated Gigabit Ethernet controllers. Those GigE controllers can also be teamed to form a single pseudo-2Gbps connection for those who just can't get enough bandwidth. The 680i SLI even includes provisions for networking quality-of-service; Nvidia's FirstPacket software allows users to prioritize outbound networking packets on an application-by-application basis. FirstPacket isn't slick enough to prioritize inbound packets, but for those looking to smooth ping times while uploading, it's a handy feature to have.

In addition to its loaded networking capabilities, the nForce 680i SLI also supports LinkBoost. This feature was left out of the nForce 590 SLI for Intel processors, but it's made a return in the 680i. LinkBoost cranks the speed of the chipset's interconnect and PCI Express graphics links by 25%, but Nvidia is quick to point out that it isn't overclocking—the chipset and motherboard has been fully qualified and validated at those higher speeds. Boosting PCIe and interconnect bandwidth by 25% is nothing to sneeze at; however, we've yet to find a circumstance where LinkBoost measurably improves performance.

The 680i SLI will be Nvidia's first nForce 600-series chipset to hit the market, but it won't be the last. An nForce 650i SLI chipset will follow for mid-range markets using the same north bridge chip but a reduced-feature south bridge. Nvidia also has a 680a chipset for AMD's upcoming 4x4 platform, but we can't say much about that just yet.