For those of us inclined to build our own systems, the two most important prongs of the program will be the add-in card and motherboard certifications. Motherboards are a key component because they'll handle much more than just supplying a pair of PCI-E X16 slots for the cards; they will also come with the SLI connector dongles needed to make the cards talk to one another. Mobo makers have expressed a desire to build SLI motherboards with different slot configs and spacing, so NVIDIA will be leaving it up to makers of SLI-ready mobos to supply the SLI connectors that bridge between the "golden fingers" connectors on the two graphics cards. Those custom-sized connectors will need to provide a solid fit and decent signal integrity in order for the whole solution to work, and NVIDIA will validate the various solutions to ensure they do. Mobo makers onboard include Abit, Asus, DFI, Epox, Gigabyte, Iwill, and MSI.
Certifications for graphics cards themselves is interesting. The fact that two different cards from different manufacturers are both SLI certified will not signal that the two cards should work together in an SLI config. Instead, the certification will simply verify that a pair of cards of the same brand are OK for SLI use. This guarantee alone is no simple thing, the company told us, because card makers may revise their cards with changes like different memory configurations over the life of the product. Most of NVIDIA's major graphics card partners have signed on for card-level certification.
Although NVIDIA has said SLI will work transparently with a wide variety of 3D games and other applications, NVIDIA wants the app-level certification to ensure that developers are using all the right tricks and techniques to best take advantage of SLI's additional graphics power. I'd expect lots of cross-pollination here with NVIDIA's "The Way It's Meant To Be Played" program. The system-level certification is aimed at OEMs, and will include participants like Alienware, Falcon Northwest, Polywell, and VoodooPC, among others.
The concept of SLI certification seems fairly straightforward, but one concern we've had about SLI certification for some time now stems from a conversation with had with NVIDIA about chipsets in which we were informed that the nForce4 will be the only Athlon 64 chipset solution certified for SLI. This utter confidence at such an early stage in the game devalued the whole concept of validation for us, because NVIDIA seemed determined not to certify competing chipsets to work with its SLI graphics tech. When we asked the NVIDIA graphics folks about this issue yesterday, they said it's not so simple as all that. For one thing, the certifications will happen for four different types of products, and none of those is chipsets. The motherboard certification, they said, will not "by design" exclude boards based on third-party chipsets. NVIDIA will require that the chipset's PCI Express implementation be recognized by the PCI SIG and that it pass testing, but the firm says "the more the merrier" on chipsets that support its SLI tech. We are still a little skeptical about whether or not NVIDIA will be able to resist the temptation to use SLI certification as a bludgeon against its chipset competitors, but we're willing to wait and watch to see what happens. If all goes as we would hope, SLI certification will be a useful tool for the consumer, not just a marketing ploy.