you should close the other duplicate thread. and correct the gfx card budget.
that psu might not be able to deliver 600w power. it has no power factor correction, it will draw more power from the wall socket than other efficient psus.http://www.hardwaresecrets.com/article/Cooler-Master-eXtreme-Power-Plus-600-W-Power-Supply-Review/1034
the 5770/6770 might be able to run on the psu. if it's old, you should change replace it with a better, 80+ rated, active pfc psu like corsair builder cx 500 v2 or seasonic s12ii 520w or antec neo eco 520c etc. low end psu components age faster and can damage reliability of the system.