At this point you want to reduce the total points of failure. Remove all cards, all but one stick of memory, all peripherals, etc. Just see if you can get it to post even if you don't have video. If you still can't get anything with that then you may want to take everything apart and check for bent pins. Reassemble the bare minimum on a non-conductive surface and try it one more time. If you get nothing then it is most likely a bad CPU or mobo.