Source: HotHardware
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For almost a year now, NVIDIA has been teasing enthusiasts with their Quad-SLI technology. It was back in January at the Consumer Electronics Show that we got our first glimpse of a Quad-SLI based system, the Dell XP 600 Renegade. That first Quad-SLI implementation consisted of four GeForce 7800 GTX GPUs, each coupled to 512MB of graphics memory, for a grand total of 2GB of frame buffer memory. Although it looked like four separate graphics cards were used to build up those early Quad-SLI systems, it was actually two. Each GeForce 7800 GX2 card as they became known consisted of a main 512MB GeForce 7800 GTX with a secondary daughter-card mounted to one side. The GPUs each got their own slim coolers, and the main- and daughter-cards communicated to each other through a proprietary link. Then two GeForce 7800 GX2 cards were installed into an appropriate nForce 4 SLIX16 based motherboard, and linked together via a pair of SLI connectors. NVIDIA also developed a proprietary switch for these early cards that allowed each 7800 GX2 card to interface with a single PCI Express X16 slot for full bandwidth operation.