total power draw is about 500w or higher depending on the voltages used. Just because it only pulls 500w doesn't mean you can get a 500w psu and be fine, most powersupplies can only output there rated wattages at around 70% ussage and it goes down slightly on higher usage due to the efficiency curve of said PSU. Its always safe to have around 100 or more "spare watts" on your PSU, in case you upgrade later and to keep the usage around 70% will have the greatest efficiency.