I'm not an expert but I wouldn't jump on the bad CPU MBO yet. I built a new pc for my son, it worked for a few days then one day only the case fan came on, nothing else, no beeps, no harddrive lights, nothing. I suspected the power supply because I reused an old PS I had. I bought a new 500watt PS and all is well.
Dred, I would take it in and just have it all tested, may just be bad PS, or could be CPU