My rig won't start with the P4 ATX connector in. I press the power and the fans twitch and stop after maybe one rotation and lights don't flicker. BUT if i take the p4 out (after unplugging the power supply and getting a fresh charge) the fans start and the hdd and power lights stay on but not the case lights that are plugged into and auxiliary fan and of course the cpu wont start. Is it the motherboard? Its not the PSU i swapped it out for another and it did the same so i swapped it back. I also tried just the motherboard with NOTHING ATTACHED only mobo and psu and the same happened.
I guess i know its the motherboard but i want to be positive.