I don't have another PSU readily available atm. I just know the entire system at least powers on when the 12V Connector isn't plugged in near the CPU. It turns on and stays on. I might have to take the PSU out of my other PC which is what I was going to use, but that one didn't post after being off for 2 months. Have to take a look at the one after work. Unplug the Vid cards and see if it turns back on.
As his pc boots without the 12v connector, it's not needed when running at low cpu load. You'll only get into trouble when the pc gets stressed. I know that when the 12v connector is plugged in, power will also be drained from it, but I just meant ist only NEEDED when under stress.
Doing a lot of gaming probably would put the stress on.
Downside right now...still no motherboard. Asus said they would do an advanced replacement on it. Ship a motherboard, then I ship the defective one back. I finally called them back and they said they declined the advanced replacement after approving me for it. No one bothered to tell me about this change. Calls to anyone who can explain this remain unanswered.
Last build for me with any Asus parts thanks to their wonderful customer service.