I have Gigabyte GA-78LMT-USB3 MB and a Rosewill 720 watt power supply. The MB Manuel states : The 12V power connector mainly supplies power to the CPU. If the 12V power connector is not connected, the computer will not start. I had the cpu cooler fan plugged in and got the wrong connector at first and when I did find the correct connector the ps would not start. How can I troubleshoot this? I have ohm meter.