Whats wrong with a computer when i put in a known good processor(after the other cpu didnt work at all) and thecomputer shows a post screen but when i shut the computer off it doesnt come back on again. Nothing is wrong with the power supply.Now as i kept trying it it came back on again . (now it never comes on again) Could it be a motherboard problem. I thought at first something was burning out the processor even though i have grease on it Why does the computer come on sometime and sometime it dont.Could the power supply be erratic. But why then did the first cpu didnot work.And this cpu worked intermittenly and now it dont work no more.