NVIDIA HAS BEEN TALKING publicly about Quad SLI for half a year now, and Quad SLI configs have been shipping for a few months in a select number of ultra-high-end PCs. Today, at long last, NVIDIA is unveiling a consumer version of its Quad SLI component card, the GeForce 7950 GX2. A single GX2 plugs into one PCI Express slot, but it actually has a pair of printed circuit boards, two GPUs, and two sets of memory chips onboard. By itself, the GeForce 7950 GX2 is an SLI setup on a stick, a dual-GPU powerhouse that fits into the same space as any other high-end graphics card with a dual-slot cooler. Slide two of these puppies into a system side by side, and you have the potential for Quad SLI-but not the reality, apparently, if you're just a lowly DIYer.