Hardware Blog

Following up on its phenomenal success producing high-end Intel-compatible chipsets, Nvidia is looking to capture more of the mainstream market. But while the 680i SLI trumped its competition on features alone, the new 650i SLI is considerably scaled back. The most noticeable example of this is found in the number of PCI-Express pathways: While the 680i SLI offered a full 46 lanes for support of up to three PCI-Express graphics cards with two getting their full slot bandwidth, the 650i SLI gets fewer than half as many lanes at a total of 18, sixteen of which must be either sent to a single graphics card or divided among two cards in an x8 plus x8 configuration.

The secret to Nvidia’s cost-cutting adventure lies in its reuse of an older Southbridge, the MCP51 as previously seen in its GeForce 6100 series for AMD. Other than not supplying the Northbridge with additional PCI-Express pathways, this older part carries another legacy feature: An ATA controller that supports four Serial ATA and four Ultra ATA hard drives, rather than the six/two split found on all of the company’s recent products. Yet, this may be a bonus for those looking to save money when upgrading by carrying over their old drives into a new configuration, and most mainstream builders will never use more than four SATA devices anyway.

One more piece of hardware dragged up from the past - and one that we weren’t hoping to see again - is the “paddle card” PCI-Express slot selector. Most of the boards we tested support either two x8 or one x16 pathway by manually removing and re-installing a small card from between the graphics card slots. Exceptions include the ECS NF650iSLIT-A, which uses permanently fixed x8 pathways for both slots, and the Asus P5N32-E SLI Plus, which uses a different Southbridge altogether. None of the remaining boards feature electronic switching found on early high-end SLI motherboards, because those would have added expense to these reduced-price products. Because the NF650iSLIT-A is always in x8 transfer mode for both slots, it will provide the sole example of performance lost to reduced PCI-Express pathways in these single-card tests.