I have an antec earthwatts 500, I want to crossfire two 5770's ati's website recommends a 600watt psu, I'm also running an amd am2+ phenom 9850 125 watt quad core and an seagate barracuda 7200.12 750gb hdd, shpuld I upgrade or will this psu work? the maximum board draw is 108watts for a single 5770