you say you cant boot into post screen ... first of all ... you say you got a 550w psu on that gama790xds4 ... check to make sure you've connected all yer pins ... ie your 8pin 12v being important (note: if your psu doesnt have an 8pin 12v connector ... it most likely wont work.)... also you're pin cfg in regards to "clr cmos" isnt set in, check ram, 1 in 1 out ... vice versa ....