lot of confusion continues to swirl around what is and isn't SLI. Shortly after the technology's arrival, some board manufacturers started coming out with "near-SLI" implementations. MSI, for example, released an nForce4 Ultra board with an x16 and an open-backed x4 slot. By using early versions of NVIDIA's driver, this enabled the board to deliver SLI-type functionality that came within 5% to 10% of true SLI. NVIDIA quickly altered their drivers to prevent such approaches from working.
More recently, DFI's NF4 Ultra-D motherboard went to market with two x16 slots but no SLI bridge included. Like VIA, DFI maintains that the twin slots are meant to enable three- and four-head video output, not SLI. However, one prominent Web site shows how the Ultra chip can be easily modded with a #2 pencil (yes, seriously) and effectively turned into an SLI—the chip construction is that similar—thus turning the Ultra-D into an SLI motherboard. NVIDIA is reworking the Ultra chip to prevent this mod from working in the future, and subsequent Ultra-D boards will carry the updated chip.
*www.reselleradvocate.com/public/ram/issues/ram40/ram40_chipsets_coverstory02.html