So Apple says: "If you choose the NVIDIA GeForce GTX 680MX on the 27-inch iMac, you get the best graphics performance available in an all-in-one computer." Is that true? The 2011 iMac that I bought supposedly had the top mobile graphics card or at least arguably the top. Anyone want to weigh in? I'm concerned about the slim design being a limiting factor for inclusion of high end graphics cards. But maybe I shouldn't be considering we have always only been talking about cards that go into laptops.