kkn ... my thought exactly .. just because it is 'new' doesnt mean it works ...
Id test that out .. or try another before i look'd hard at the MB.
CrossHair II ? Those things were all but bulletProof .. if there arent any blown caps
on it ... & the cpu is good .. it should fire.
but if it doesnt switch'n on and then off (cpu)... id say you still have a bum psu.c.