I would give up the OC and stretch a bit for a 1070: http://xtremmedia.com/?q=cconfig/view#A045786,A042967,A002949_op,A033063,A047524,A027134,A026839,A046462,A038907,A001299_op

Put Windows 10 64 bits on it, for now DX12 doesn't add anything but it's better to be prepared. More than one colleague has bought licenses for €10 on eBay and so far no one has complained.