The K series quadros are better than the non-k series. They are newer and usually significantly out perform the non-k cards. As for performance, the quadro cards are not built for only speed, they lose to gaming cards in render time because they sacrifice speed for precision. If you need a very detailed CAD, go for the quadros, if you want the fastest render, go for the gaming cards. I do a little CAD on a gaming card and the loss of detail is not significan, at least to an untrained eye (like mine). As for dual cpus, it depends on how you use it. If you do choose to go for dual cpus, it will mean that any program running on your CPU will run really fast. For just CAD, this would be a waste of money, because CADs normally run mostly on the GPU. Unless you are running a server on your computer, a single quad- or hexa-core cpu would be better than dual cpus. This will also free up some money to spend on a bleeding fast gpu. As for builds, look here (http://www.cpubenchmark.net/) for a good cpu ( there is a performance to dollar comparison tool) and you can also look there for a good gpu and hdd/ssd. For the motherboard, look at a site like newegg (www.newegg.com) and choose mobos with the comparable socket (very important). Good luck and I would love to hear what you eventually choose.