The GT 520 will bottleneck you GPU. What the hell is that even supposed to be for? The performance you will be get will be like 2 x GT520s. The RAM; dual channel? Maybe you can opt for quad channel or I think it should do quad channel itself.. CPU; wait. Once they get IB then you can select one, the i7-3770K should be the equivalent for that. Should be same price, around 15% faster, and more power efficient. Drop down to a 850-watt-ish PSU with good power efficiency. This was just my two cents.
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PS. The hell! There is a GTX 680 available for 22 bucks less, and much more power efficient and you go with the GTX 580?
No hurt intended, but it is a good thing that you got your build checked here.