SLI will be only PCI express. It's the only way to do it, since there are never 2 AGP slots. Interestingly, PCI Express is being used as the interface for a lot of budget and mid-level cards. Why? I'm not entirely sure. The truth is it doesn't even provide any real benefit to high end cards, yet (aside from SLI capability). So of course it doesn't help lower end cards either. One possibility is that it's an "OEM checkbox" feature, basically something that exists so that high volume OEM's can put "featuring new PCI express graphics system!" on the box and theoretically sell more units. As for the "SLI" technology itself, using multiple boards or multiple chips on a single board has been around for a while. 3dfx pioneered it in the consumer space back with the Voodoo II, but ATI and others have since dabbled in it. The only reason multi-card solutions haven't been found in the consumer market lately is because the AGP spec only allows 1 slot, and pairing an AGP board with a PCI board would create a large imbalance. The "SLI" technology that will be used for the nForce4 is not the same as the old 3dfx SLI, which used a ScanLine Interleave (hence "SLI") process for splitting up the work load. Most likely it is only the name and the basic experience and understanding of how load balancing works in graphics rendering that nVidia drew from their 3dfx acquisition. - Oshyan