add up your watts
you should use 600-700 psu with 42-50 amps - my son is running a x1950 pro with 560j @4.1ghz and its crashes alot of psu's under 35 amps - we test parts in his system
read those links on how to size it
silverstone strider 600 is $110 at east luna i think its more at newegg?