The Nvidia 8 series cards use two pci-e power inputs; I expect that it would take a ridiculous amount of power to run both of them safely and efficiently!
As for a case, it depends what style you're looking for. I personaly would go for either the lian li v1000+ or my current case, the NZXT Lexa which is very spacy , comes with some nice added extras like a carrying harness, has an awesome brushed aluminium front bezel, LCD temp. display, and most importantly, a 120mm fan in the window, over the graphics card slots instead of the cpu, so it blasts cold air onto your graphics cards!
http://www.newegg.com/Product/Produc...82E16811146018
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