If you want to save some money, I would recommend the X4 as 6 cores won't get you much better performance in many applications as of right now but if you want to be ready for future applications that take advantage of more cores, you can't go wrong with the X6.
Apart from that, everything else you choose looks just fine. Good price on the power supply you picked too at 630W. Should provide good performance for what you're getting now.