Make sure you upgrade your PSU. I would recommend a 900Watt or higher PSU.
You don't need a 900W PSU. You need a high-quality PSU such as Seasonic X-series, 750W tops but 650W should do fine too. Anything which is not from a known brand is utter junk, and even within a brand some products are good and others not so much.
you might be able to go with a smaller one, but your efficency will be lower, plus overclocking does use the juice more. I still stand by my recommendation. A bigger PSU will have better effiencies.